Democrats are hungry for a blue wave in the November election, and a series of recent polls has them thinking they could pull off victories in some deeply red territory that would have seemed unthinkable a few months ago.

Expectations for the party are so high that one could envision a fair amount of disappointment in the party — and celebration among Republicans — if Democrats don’t shoot the moon on Election Day and take control of both chambers of Congress.

“I think Democrats are in striking distance in enough states to have a really good day,” CNN senior political commentator David Axelrod said Monday on “The Arena” with Kasie Hunt. “But it wouldn’t surprise me if they fell short of taking over the Senate.”On the other hand, Axelrod wouldn’t be surprised if Democrats got 53 seats, he said. “It really depends on how high this wave is,” he said. The expectation, though, is that there will be degree of wave.

In 2022, after the Supreme Court overturned Roe v. Wade, Democrats and President Joe Biden all but celebrated that they lost only nine House seats and control of the House of Representatives.

“While the press and the pundits are predicting a giant red wave, it didn’t happen,” Biden said a day later, describing the results as “a good day for democracy” even though Republican control of the House put a stop to his legislative agenda.

In 2018, after the GOP lost 41 House seats and control of the chamber, Trump pointed to Republicans maintaining their Senate majority and bragged that they “dramatically outperformed historical precedents.”No matter what happens this year, Trump is likely to allege there is voter fraud — regardless of whether there is any evidence — and to try to claim some form of victory.

Democrats are excited about this election. They held a nearly 10-point advantage over Republicans in a recent ABC News / Washington Post poll when voters were asked which party they will support in November. In Senate races, Democratic candidates are competitive against Republicans in red states including Alaska, Iowa, Kansas and Texas.

There are also tight races in purple states like Michigan and Georgia, where Democrats are hoping momentum can save seats they currently hold. The inevitable post-election review of polling will hinge on whether pollsters this year captured or over-indexed Democrats’ enthusiasm. The president’s party almost always loses House seats.

Only twice in the past 100 years has the president’s party lost at least some – and frequently a lot of — House seats.

The two exceptions were in 2002 under President George W. Bush, in the run-up to the US invasion of Iraq after 9/11; and in 1998, when the dot-com boom buoyed the economy and there was a public backlash to the impeachment of President Bill Clinton. It varies.

A change of a few seats can be a very big deal. When Democrats lost nine seats in 2022, they narrowly lost control of the House, a clear defeat. But it was far from the landslide many expected that year.

Much bigger swings can happen. In 1994, Democrats lost 54 seats in the so-called Republican revolution of Clinton’s first midterm. In 2010, the so-called tea party revolution, Democrats lost 63 seats, something then-President Barack Obama called a “shellacking.”In both midterms, Democrats lost control of the House.

During Trump’s first midterm, in 2018, Republicans lost control of the House when they lost 41 seats.

Only 35 Senate seats were up for grabs in 2018; senators serve six-year terms, and only a third or so are on the ballot in any given election. Of the 35 seats up in 2026, only 10 are on CNN’s list of key races. Democrats need to win eight of those 10 to reach 51.

Of those key races, three — Georgia, Michigan and New Hampshire — are seats currently held by Democrats. Seven of the key race states — Alaska, Iowa, Kansas, Maine, North Carolina, Ohio and Texas — are currently held by Republicans.

It’s hard to imagine a swing on that level in this election because there are fewer hotly contested seats after years of gerrymandering in many states. Only 21 seats are labeled as “tossup” by the nonpartisan Cook Political Report. Of those tossup seats, 15 are held by Republicans and only six are held by Democrats.

Ten Republican-held seats are either solidly, likely or leaning toward Democrats, according to Cook. One more is held by a lawmaker who left the GOP to become an independent. Eight Democratic seats are either solidly, likely or leaning toward Republicans.

It means Democrats may only need to win one or a few tossup seats to take the House majority. But if Republicans win a large portion of those tossup seats, they will be able to claim they breached the wave.

The House and the Senate can go in opposite directions. In the two most recent midterms — Trump’s first-term midterm in 2018 and Biden’s midterm in 2022 — the president’s party lost enough House seats to lose control of House of Representatives, but actually gained seats in the Senate.

In 2018, Republicans flipped four Senate seats and Democrats flipped two, gaining two seats for Trump’s party even though Trump’s approval rating was quite low at the time. In 2022, Democrats flipped one seat when the national mood was against Biden.

Control of either the House or Senate has changed with regularity in recent years, to the extent that every election is a change election of some kind. But only twice in the past 100 years — in the 1994 Republican Revolution and the 2006 Democratic wave against the war in Iraq — did both the House and Senate change hands in the same cycle.

President Donald Trump’s low approval rating is dragging down Republican candidates, and some recent polling has Democrats dreaming about wins in unexpected places.

Each of these races is also unique. The Democrat running for Senate in North Carolina is a popular former governor, Roy Cooper. The Democrat running in Georgia is an incumbent, Jon Ossoff. The Republican running in Texas is the state’s relatively unpopular and scandal-plagued attorney general, Ken Paxton. In Kansas — where there hasn’t been a Democratic senator in nearly 100 years — the moderate pastor running as a Democrat has the party hoping.

Polling in both states suggests tight statewide races for Senate and governor. Democrats have long tried to manifest the idea that a Senate seat in Texas could be up for grabs. It hasn’t happened since 1988, the year before Talarico was born. In Kansas, an independent candidate led an unpopular Republican in pre-election polling back in 2014, only to lose on Election Day. So it would not be unprecedented for Republicans to re-surge in these states.

If there’s a true blue wave, start looking even further into red states, like in South Carolina, where Annie Andrews, the Democratic doctor who has been the subject of insults by Trump, wants to unseat Sen. Darline Graham, who was appointed to fill the seat left by her brother, Lindsey Graham, after his death this year.

Both chambers are narrowly divided. Democrats would need to net four seats in each chamber to gain a majority.

In fact, Republicans’ House majority is the narrowest in history. Headed into Election Day, there are 218 Republicans — a bare majority in the 435-member chamber, although the one independent member, Rep. Kevin Kiley of California, votes with Republicans for administrative purposes. There are 214 Democrats and two vacancies, one left by each party. It would be a major disappointment for Democrats if they don’t pick up a few seats.

In the Senate, there are currently 53 Republicans, 45 Democrats and two independents who function like Democrats.

Democrats would need to reach 51 in order to control the 100-member chamber, since Vice President JD Vance, in his role as president of the Senate, casts tie-breaking votes.

Trump has been setting expectations for his entire second term, acknowledging the history that the president’s party usually loses some midterm seats. He has also been governing with a kind of wild abandon, getting as much done as possible as if in anticipation of a more hostile Congress in the second half of his term.

Democrats in charge of either the House or Senate would mean much more oversight of Trump’s administration in the form of investigations and hearings — powerful tools in exposing an administration to sunlight and trying to shape public opinion.

They would also have more control over the US budget. Trump has made a point of not spending money appropriated by Congress, but a Democratic majority in the House and Senate could put new restrictions on Trump in spending bills. That power would be less if Democrats took control of only one chamber.

There will be harsh limits on Democrats if they do take control of the Senate. In no plausible scenario will either party have the kind of supermajority needed to overcome a filibuster. That means spending bills would ultimately need bipartisan support — and buy-in from the White House — to pass.

Trump has shown a willingness to allow government funding to lapse even when Republicans control the House and Senate.

Republicans tried to inoculate some of Trump’s priorities from spending fights; they bypassed the filibuster and used budget reconciliation earlier this year to fund Immigration and Customs Enforcement for multiple years, for instance, for the rest of Trump’s term. They knew history suggested a wave might be coming.