Voting is set to start from around 1pm GMT today and run until the early hours of Wednesday morning.
Trump has boasted about the economy and hammered away at illegal immigration in the closing days of the campaign as he seeks to hold onto a majority in Congress and push his legislative agenda.
Democrats would need all five of those races to go their way presuming they hold the seats they're expected to, plus pick up a seat in a longshot like Texas or Tennessee or MS to claim a majority.
An IPSO poll conducted ahead of the mid-terms found "investigating and potentially impeaching" Trump was the number one priority for Democratic voters.
A man wearing a Space Force shirt documents the scene before a campaign rally with President Donald Trump at the Bojangles Coliseum on October 26, 2018 in Charlotte, North Carolina. I think we need a president and leadership that appeals to the better angels of folks.
Cruz said he wants a border wall and no amnesty granted to anyone who enters the USA illegally.
"We continually assess the capabilities of our facilities throughout the Southwest border and have been making - and will continue to make - necessary preparations", the statement said. And that is an invasion.
Whether they flip the House or not, Democrats are still expected to gain seats in the chamber, given the favorable political environment for Democrats. This small error, along with the fact that some undecided voters unexpectedly voted for Trump, handed him the electoral college. "That is an invasion of our country". But each of these possibilities have been accounted for in pollsters' projections that there is a six in seven chance that Democrats will take back the House - so I'd say it's pretty likely this is what will happen.
Former President Barack Obama has been campaigning with Democratic candidate for Georgia Governor Stacey Abrams. "You vote, you might save a life". "When you vote, Illinois, you can choose hope over fear", he said.
"The only check right now on the behaviour of these Republicans is you and your vote", Obama told supporters in Gary, Indiana, during a rally for endangered Democratic Senator Joe Donnelly.
Democrats' fate depends upon a delicate coalition of infrequent voters - particularly young people and minorities - who traditionally shun midterm elections.
He accused Democrats on Monday of seeking to make America "a giant sanctuary city for drug dealers, predators and bloodthirsty MS-13 killers".
Striking a dark tone at a rally in IN on Monday evening, Trump accused Democrats of "openly encouraging millions of illegal aliens to break our laws, violate our borders and overrun our country".
"The big picture is that midterm elections go against the president's party", noted John Fortier of the Bipartisan Policy Center in Washington.
"I think they will be both miserable and emboldened", says Rove. But several critical state governor positions may go to the Democrats. It's an area that serves as a pretty good example of Republicans' problems in the Trump era with highly educated voters in suburban areas, especially women. RealClearPolitics puts Trump's average approval at about 43 percent, with 53 percent disapproving.
"If the radical Democrats take power they will take a wrecking ball to our economy and our future", Trump declared in Cleveland, using the same heated rhetoric that has defined much of his presidency.
The Wesleyan Media Project, which tracks campaign ads by subject matter, said in September that the president was mentioned negatively in less than 5% of TV ads to that point - rarer than in the previous three congressional midterm elections.
He noted that Republicans now hold 33 governorships, compared to 17 for the Democrats.
If Democrats win enough House seats to reclaim the majority, Trump would face a shift in the balance of power in Washington.