Republican President Donald Trump’s low approval ratings, voter concern over high prices and dissatisfaction with the Iran war have led many analysts and opinion polls to predict significant Democratic gains in Tuesday’s midterm elections.

But six analysts and party strategists told Reuters several factors could prevent Democrats from turning those favourable political conditions into a landslide, even if the party ultimately makes gains in Congress.

Recent opinion polls have shown Democrats increasingly competitive in once reliably Republican seats and the party has been expanding its efforts into Trump’s conservative heartland.

Democrats are widely expected to have a good election night, but the scale of any victory is still uncertain.

Here are six reasons Democrats may fall short of expectations.

Fewer competitive House races

The number of competitive US House races has shrunk sharply over the past three decades as partisan polarization and redistricting – including gerrymandering – have made more seats safely Democratic or Republican.

As a result, analysts estimate that only about 40 to 50 of the House’s 435 seats are truly competitive this year.

Most expect Democrats to retake the lower chamber from Republicans, but with a majority of perhaps 5 to 20 seats, limiting the scope for gains like those in 2018, when Democrats picked up 41 seats.

Bill Galston, a former White House adviser to President Bill Clinton, said if Democrats gain even 25 House seats, “they’d have a working majority, but not a huge one.”

Such a majority would give Democrats control of the House but little room to maneuver, making it harder to pass contentious legislation or claim the sweeping mandate associated with past ⁠wave elections.

Senate majority no sure thing

While Democrats are favored to make gains in the 100-member Senate, achieving the net gain of four seats needed for a 51-49 majority remains far from certain because many of their top pickup targets are in states Trump carried by wide margins in 2024.

David Wasserman, an elections analyst at the nonpartisan Cook Political Report, said Democrats must make breakthroughs in states Trump carried by double digits. Even a national swing of 10 percentage points toward Democrats would likely leave the party two seats short of a majority, he said.

Democrats also face tougher-than-expected contests in states they had hoped would be safer, including Maine, New Hampshire and Michigan.

“Republicans are hanging very close in those races,” said Andrew Busch, a public policy professor at the University of Tennessee, Knoxville, and author of a history of midterm elections.

“That’s not necessarily what you would expect if things were going well for Democrats across the board.”

Turnout

Opinion polls show Democratic voters more enthusiastic than Republicans, but strategists caution that such Democratic constituencies as young, Black and Hispanic voters have historically turned out at lower rates in midterm elections than in presidential years.

Surveys show persistent skepticism among these groups towards both parties, especially over the cost of living. If turnout among those groups falls short of expectations, Democrats could underperform on Election Day, analysts said.

Early voting data in states that register voters by party showed higher Democratic engagement. But Republicans argue that many of their supporters traditionally wait ⁠until Election Day to vote.

In the 2022 midterms, voters aged 50 and older made up nearly twice as much of the electorate as those under 50. In recent years older voters have leaned Republican, according to exit-poll surveys.

Republican money advantage

Republicans entered the campaign’s final stretch with a substantial financial advantage, although spending in key races so far has had mixed results.

Republicans held a cash advantage of several hundred million dollars heading into the final weeks of the campaign across their national party committees and major allied super PACs, according to committee filings and Federal Election Commission data.

Trump spent more than $277 million, mostly through his MAGA Inc. super PAC, on a late TV and direct-mail blitz to aid struggling Republican candidates, according to Federal Election Commission data.

Tesla (TSLA.O), opens new tab CEO Elon Musk spent roughly $366 million during the ⁠midterm cycle, including $276 million since July, to support Republican candidates.

Republicans outspent Democrats by $188 million in Senate battleground advertising by the end of September, according to AdImpact, which tracks advertising spending.

“Any time you have one side with a big financial advantage and the ability to pour it into races at the last minute, it can tip the result of close races,” Busch said.

Polls have missed Republican strength

Opinion polls have frequently underestimated Republican support in recent election cycles. Reuters/Ipsos polling shows registered voters favoring Democrats over Republicans by 47% to 35% on the ⁠congressional generic ballot.

The largest polling misses came when Trump was on the ballot. Trump, who is not on the ballot this year, has urged supporters to treat November’s election as if he were.

Polls significantly understated Republican strength in the 2014 midterms, when the party won a sweeping Senate victory. But midterm polls in 2022 underestimated how well Democrats would perform.

Socialism attacks could resonate

Trump and many Republican candidates have sought to paint Democrats as socialists and extremists who pose an existential threat to ⁠the country.

Democrats in competitive races are increasingly declaring themselves proud capitalists, worried that the Republican tactics could sway critical independent voters.

Republicans are highlighting victories by members of the Democratic Socialists of America movement and progressive candidates in Democratic primaries to portray the whole party as socialist, even though fewer than two dozen of them scored wins this year.

Galston said the attacks could resonate with some wavering voters and influence close races.

“It might be effective at the margins,” Galston said. “It could reduce the Democratic advantage by one or two points in the close races.”