For months, Democrats have drilled their central message into the minds of voters: if Republicans strengthen their grip on Congress, they will destroy your health care, including coverage protections for people with pre-existing medical conditions.
In the House, Democrats need a net gain of 23 seats.
The nonpartisan Cook Political Report shifted nine House races toward Democrats in a new forecast published Monday, the Hill reported.
"We're not some fringe element of the Democratic Party". This would seem likely even in a neutral environment, and history shows that these "toss-up" races tend to go strongly in the direction of the party with the electoral momentum.
Firstly, it would mean the party could block legislation proposed by the president.
Among other significant findings, President Donald Trump's job rating among likely voters is 46 percent approve, 52 percent disapprove, which is the same as in October. If the map were anywhere close to neutral, and the environment were as it is, Democrats would be virtually guaranteed a House takeover right now. Which strategy you prefer depends on whether you think there are more votes to be had at this point from group one or group two.
The Republican president has also been warning the other party will destroy a healthy United States economy if they win the keys to power.
How it would happen: Let's assume we're underselling the size of the blue wave.
As in 2016, Democrats are more outspoken about how they're going to vote in the upcoming elections than Republicans and unaffiliated voters are, Rasmussen found. Top congressional Democrats are throwing cold water on moving to impeachment quickly, but they say if there is evidence that emerges from the special counsel's probe of any wrongdoing, they don't rule out Judiciary Committee action.
Anxious Republicans privately expressed confidence in their narrow Senate majority but feared the House was slipping away.
They have seven open congressional seats to fill, the most in decades.
The Democratic incumbent in North Dakota, senator Heidi Heitkamp, is significantly trailing Republican challenger Kevin Cramer in the polls.
But on the eve of the election, in a packed airport hangar in Cleveland and at other Trump rallies across the nation, the stakes are different: a vote to protect a leader they see as under siege, whose inflammatory rhetoric is a necessary price for a norm-shattering era of change. Bloomberg photo by Aaron P. Bernstein.
The two parties were also tangling in several crucial governors' races, including in Midwest battleground states such as Wisconsin, Ohio, Iowa and MI.
Several Senate races are also extremely close.
Trump echoed what he's been saying for weeks as he stumps for Republican candidates for the House, Senate and governor's mansions: Democrats will throw America in reverse.
A White House that has struggled to stay on course under favourable circumstances would be tested in dramatic ways.
In the 69th Illinois House district, Rep. Joe Sosnowski, a Republican, will defeat Angie Bodine, 58 percent to 42 percent.
Whether at home or overseas, countering communism and socialism has emerged as one of the key themes unifying Trump's efforts.
In the midst of a six-day national blitz of rallies ahead of Tuesday's election, Trump will also appear later on Sunday in Tennessee, which hosts a vital U.S. Senate race. It could result in states such as Nevada or even Arizona staying under GOP control and deliver states like Florida, Indiana, Missouri and Montana.
How many undecideds or "soft Republican" voters will decide to switch last minute to cast a protest vote against Trump because of stuff like this?
The GOP is expected to keep control of the closely divided U.S. Senate. "I'm terrified. We're going to a place I just don't understand". Trump warned Americans would "lose all of their money" if the GOP was defeated because the stock market could take a hit. "What kind of politics we expect is on the ballot".
Pollster John Zogby said Democrats have a "slight edge" over Republicans in the House, but added it was possible the party could win the popular vote and still fall short of the seats required.
'We need somebody who can stand up to Trump, ' one candidate for local office told the crowd. You see what's happening with them. "A lot of things are offensive", Mr Trump said.