One of the longest-running streaks on Capitol Hill seems poised to keep going strong when all the ballots are counted after Tuesday’s elections.

Not since 1952, when Dwight D. “Ike” Eisenhower swept into the presidency and brought with him a Republican-controlled House, has the majority changed hands when Americans also elect a president. Instead, ever since, the House majority has only changed parties during midterm elections, beginning two years after Eisenhower’s victory, with the Democrats’ wave in 1954 that gave them a majority until the historic 1994 Republican wave during Bill Clinton’s first midterm election. The other party-changing moments, 2006 and 2010, also came in midterms.

And despite the most volatile presidential election in decades, the outcome in the House increasingly looks as if it will leave House Speaker Paul D. Ryan (R-Wis.) with a slightly more narrow majority to navigate.

The two most trusted, independent analysts — the Cook Political Report and the Rothenberg & Gonzales Political Report — have estimated that more than enough Republican-held seats are in play to give Democrats a chance at the majority. Cook’s analysis, overseen by David Wasserman, rates 40 Republican seats as competitive. Nathan Gonzales, running the Rothenberg analysis, puts about 35 Republican seats in play.

Democrats need a 30-seat gain for the majority, and if this were truly a wave election year, it wouldn’t be a stretch for them to win nearly every competitive race along with a few unexpected seats and claim the majority — that’s what happens in political waves.

But Wasserman and Gonzales conclude that the political undertow of Donald Trump’s candidacy is mostly unique to his own brand. “The presidential race may be inducing whiplash, but the House battleground remains relatively stable in the final week,” Wasserman wrote. He gives Democrats a top level of netting 20 additional seats — but also an equal chance of just single-digit gains.

Gonzalez’s last report gave Democrats a chance at gaining 15 seats, but also suggested single-digit gains were just as likely. (Gonzalez’s former partner, Stuart Rothenberg, founded that report and now writes for The Washington Post.)

If these predictions hold up, House Republicans will end up in roughly the same shape as four years ago, when their 2012 nominee, Mitt Romney, presented a much more appealing figure in key swing districts than Trump does today. Back then, the GOP ended up with 234 seats.

There are plenty of factors behind the Republican resiliency in these House races, but the biggest factor might just be an odd quirk among swing voters: They only tend to break sharply against one party’s congressional incumbents if the lawmakers are directly tied to an unpopular president.

That’s why midterm elections, over the last 25 years, have produced the biggest swings from one party to the other, like the 30 seats Democrats gained in the “six-year itch” midterm of George W. Bush’s presidency.

President Obama’s first election in 2008 produced a large Democratic gain, of 21 seats, but his party already held majority and was just running up the score. The more normal result is the eight-seat gain Democrats made in 2012, which still left them 17 seats shy of the majority.

In both 1996 and 2000 the minority leader, Richard Gephardt (D-Mo.), thought he had a chance at claiming the speaker’s gavel, but in each instance Democrats picked up fewer than five seats. Most agonizing of all was 2000, when Gephardt needed to win just six more Democratic seats to win. His party gained just two more districts, leaving the Republicans with a 221-seat majority, the smallest majority since the mid-1950s.

The most likely scenario for the House majority to switch hands during a presidential cycle seems to be when the party holding the White House also runs Capitol Hill, and that party loses the top-of-the-ticket race and craters down-ballot races. That’s what happened in 1952 when Eisenhower’s Republicans took charge after 20 years of Roosevelt-Truman run in the Oval Office.

The Senate majority is only slightly less stable than the House, having changed hands once, in 1980, during a presidential year since the Eisenhower days.

Trump would seem to be the perfect presidential nominee for House Democrats. House Minority Leader Nancy Pelosi (D-Calif.) often calls him the “gift that keeps on giving” because of his intemperate remarks toward women and minorities as well as policy proposals that traditional Republicans consider dangerous.

Yet there seem to be limits to the gifts that Trump can give. Strategists in both parties privately say Democrats lack that dynamic today and that Trump’s sometimes outlandish statements make him so unique that it makes it more difficult to connect his views to others. Many Republican seats are also safe due to recent redistricting decisions regardless of who is at the top of the ticket.

The Democratic Congressional Campaign Committee made a concerted push to field as many candidates as possible in suburban districts with high education levels, because those voters have been the most offended by Trump’s candidacy. Strategists believe that the declining amount of ticket-splitting would give Democrats a chance to win in places that seemed previously out of reach.

It has worked in limited fashion. The DCCC has put longtime GOP incumbents, such as Reps. Darrell Issa (Calif.) and John Mica (R), on the defensive like never before, in suburban districts that have turned away from Trump.

Meanwhile, younger Republicans in districts breaking heavily against Trump are still in the fight, such as Rep. Bob Dold (R), who represents the suburbs north of Chicago. Clinton is poised to win the district by more than 20 percentage points, according to both party estimates, maybe even 30 percentage points, but the DCCC has not put this race away and is spending feverishly down the stretch to win it.

The problem seems to be many of those well educated suburban voters don’t believe their representatives, such as Barbara Comstock (R-Va.) and Mike Coffman (R-Colo.), are the same as Trump. Democrats have run relentless ads linking those two Republicans to Trump, and some Democrats believe that Trump has been a gateway to get voters to pay attention to positions taken by these Republicans that are more conservative than these swing districts would normally support.

Republicans privately concede those Trump attacks have done some damage to their candidates, but it’s mostly just energized liberal voters there. The independent-minded voter working in the Dulles Corridor IT sector, or in the eastern suburbs of Denver, has yet to be convinced that voting for Comstock and Coffman is a vote for Trump.

This could be bad news for House Democrats. A Hillary Clinton presidency might mean a bad 2018 midterm for them, digging the party deeper into the minority. And, as history shows, the presidential year of 2020 isn’t likely to produce a new House majority either, making it possible that their next real shot at the majority could be six years away — if Republicans hold the Oval Office by then.