2024 US election: the Senate elections will prove decisive for presidential power

2024 US Election: also very much about the US Congress

The 2024 US Election is not just for president, but also for all 435 of the House of Representatives, who face election every two years and about a third of the US Senate, as Senators serve six-year terms. This year, 34 of the 100 Senator seats are up for election. Under the first two years of Biden’s term as president (early 2021 to early 2023), the Senate was controlled by the narrowest possible of Democratic “majorities” of 50-50 plus Vice President Harris’ tie-breaking vote. That majority improved slightly to 51-49 in the last two years of his term after the 2022 mid-term elections. 

The House of Representatives was also narrowly Democratic with a 222-213 majority in the first two years of Biden’s term. But the 2022 mid-term elections saw that flipping to that same narrow majority, this time for the Republicans of 222-213. 

House elections: most likely to go with the President, but….

It’s no secret that US voters are becoming increasingly divided on their political views. This is reflected in a collapse in “split-ticket” voting, which means a voter might choose different parties for the elections on election day: for example voting for Harris for president but for a Republican for the local House seat. 

More on split-ticket voting

In recent elections, strong majorities of voters have voted straight across the ballot for a single party. The 2020 election was the most extreme in recent elections, you can go down a rabbit hole at fivethirtyeight.com on the subject with this article if you like, but the gist was that in the 44 states with two candidates on the ballot in most of their House elections, the president underperformed our outperformed the opposing party by less than 5% in each state.

This voting pattern means that the House is likely to go with the party of the president unless the vote is extremely finely balanced, in which case it could be the random handful of those House elections that tilt the outcome either way. That’s because most House districts have a heavily partisan tilt, often by design and due to manipulation of the drawing of voting districts. So only the strongest of victories by either side would create a significant majority for either party. Of the 435 House seats, only about thirty are seen as competitive by observers in the 2024 election. An extremely-finely balance general popular vote scenario, by the way, would strongly favor and perhaps almost guarantee a Trump win for president, due to the Electoral College system for electing a president.
 
Compare this modern partisan reality to the very different 1980’s. One of the modern era’s high points in split ticket voting was when President Reagan enjoyed a massive popular mandate and won the 1984 US Presidential Election by a landslide. But voters trusted Democrats in House of Representative elections, where they enjoyed a 255-177 majority over the Republicans after that same election. That didn’t matter so much for Reagan, who was able to cooperate with Congress to get significant tax cuts and spending bills passed because he enjoyed so much popular support. 

So again, unless we are at a sub 2% and maybe even smaller split in the overall popular vote for the two sides in November, we can assume the House election outcomes will go to the party that wins the White House. But the Senate situation is far more likely to generate some drama, especially in the event of a Harris win.

Senate elections: most drama in the event of a Harris win.

The potential for Senate election drama this year is down to a handful of key Senate election races that will decide whether Harris, even if she wins quite comfortably, will have much power as president. That’s because the Senate election map looks very unfavorable for the Democrats this year. If Trump wins the presidency, on the other hand, Republican control of the Senate looks a given, as we look at below.

Going into this election, the Senate is very closely divided 51-49, with 51 members who either are, or who vote with, the Democrats and then 49 Republicans. Here are some of the factors pushing the odds in the favor of the Republicans retaking control of the Senate this time:

• 23 of the 34 Senate seats up for election are already held by Democrats or Independents who vote Democratic. If Democrats want power in the Senate, they can only afford to lose one seat and then must win the presidency to maintain the slimmest of majorities via the vice-presidential tie-breaking vote in the Senate*. 
  
  
• The 11 Republican-held seats up for election look easy for the party to hold, unless Harris opens up a huge lead on Trump by Election Day, in which case possibly one in Florida and even one in Texas might be in play for the Democrats.
  
  
• Two Democratic-controlled seats are at high risk of falling to Republicans. One is a sure thing: independent Joe Manchin’s West Virgina seat. Manchin, who voted Democratic but quit the Democratic party recently, is not running for re-election in a state that is extremely pro-Trump, and the popular Republican governor Jim Justice is running and looks a sure winner. The other seat at risk is in Montana, a state that voted 16 points in favor of Trump in 2020. Jon Tester, the Democratic incumbent there, was elected in 2018. If Democrats lose these two seats and don’t pick up a seat currently held by Republicans, they lose control of the Senate.

In short, the Senate is a lock for the Republicans if Trump wins the White House, but the Democrats retaining the Senate requires large- and likely very large surprises in favour of the Democrats in at least two Senate races.

Small update to the above on September 13, 2024: A very interesting situation is developing in Nebraska, a generally very Republican-dominated state. The incumbent Republican, Deb Fischer, is running against an independent candidate, Dan Osborn. The Democrats are sitting out the race. There is very sparse polling available, but a late August poll suggests Osborn is running neck and neck with Fischer. His views are mixed, but a win by Osborn could certainly thicken the plot for the overall partisan lean of the Senate. See more coverage on this story.
 

Reminder: Split Congress means a weak president on taxation and spending policy.

It’s worth underlining again – all three of the Presidency, the House and the Senate must be controlled by the same party, or the post-election scenario immediately defaults to gridlock and no ability to forward any major agenda. That’s at least in terms of taxation- and spending policy priorities. One exception, with or without a gridlocked Congress is that the president enjoys the ability to shape foreign policy and even tariffs (if they are imposed on grounds of national security. ). So, Trump’s promise to impose massive new tariffs if he wins wouldn’t need Congress and would have very significant impact on the economy.

Recent big policy moves have only come when president has Congressional support

Trump’s huge tax cuts in 2017 were only possible because the Republicans also controlled both houses of Congress. In the 2018 mid-terms, they lost control of the House to the Democrats. And don’t forget that the Biden agenda only barely made it over the finish line in the 2020 election. Control of the Senate for the Democrats was not ensured until a Democrat won a run-off Senate election in Georgia on January 5 by a slim margin, just a day before the riots at the Capitol. After that election, the Senate was divided 50-50.
This gave the Democrats the ability (via the vice-presidential Senate tie-breaking vote*) to enact his many and very large spending bills in 2021.

Then Republicans narrowly took control of the House in the 2022 mid-term elections, putting the government back into gridlock. The US system is so different from countries with parliamentary systems and coalition governments, even minority coalition governments. It really is a winner-take-all setup, as well as a “winner must take all to get much done” in the case of the major political institutions and branches of government. The US founders intended it this way, and the US has had plenty of volatile episodes over the last 248 years of its history when politicians and citizens are sharply divided over their beliefs and vision, when only a tiny majority gets the full say.

Voter turnout is key for both parties for a sweep

It’s easiest to imagine a Republican sweep scenario - taking the White House and both houses of Congress - because the Senate map looks so easy for the former president and he won the House in 2016 even when he lost the popular vote by over 2%. The storyline in the Republican sweep scenario would likely be along the lines of popular revolt due to the runaway top voter concern: inflation. Fairly or not, voters associate inflation with the Biden administration because it happened on his watch even if Trump and Congress and the Fed showered the US economy with endless free money in 2020, the pandemic breakout year. Trump also rates higher in polls as tough on immigration, a top voter concern for many.

What could bring that surprise “Harris Sweep” scenario? Perhaps from greater turnout than expected among new voters, perhaps young women. They may turn out more than historically on the abortion issue after the US Supreme Court overturned the right to an abortion at a federal level last year. The three justices that Trump appointed made this possible. Presumably these new women voters will vote Democratic across the board if they vote Harris.

Voter turnout among surprise demographics is what the last two election have surprised the pollsters with: because polls have a hard time picking up on the intensity of the motivation to vote, and new voter groups showing up that have traditionally not voted. The 2020 election, at 66.8% participation rate, had the highest turnout since 1992, when third-party candidate Ross Perot was in the mix. The turnout for this election is also likely to be very high and we’ll have to stay on our toes on all of these elections through Election Night and possibly even beyond if we get the (inevitable?) contested results.

*Vice presidential tie-breaking vote.
The US constitution stipulates that, while the Vice President yields no practical power day-to-day, he or she does have the power to vote in the Senate when there is a tie, which actually does mean considerable real power in those rare instances. For example, VP Harris has voted 49 times at the time of this writing, to break ties in the Senate – a record - but only one more time than the tie-breaking votes cast by Trump’s VP Mike Pence. But there is a complicating factor here as well: when the Senate vote is so finely balanced, any single senator with a strong opinion can become a “kingmaker”, holding up major legislation from passing or requiring extensive amendments before voting in favor. This happened in 2021, when then-Democrat, now Independent Joe Manchin of West Virginia held up Joe Biden’s largest spending bill, the Inflation Reduction Act for months before it could pass. Former Arizona Democratic- now Independent Senator Kristin Sinema made similar moves in recent years.