But no one has the crystal ball to tell who will win, especially after pundits, polls and political soothsayers have been wrong before.
Swamped by a tidal wave of Democratic cash, Republicans entered the final 72 hours of the midterm campaign scrambling to preserve their slim Senate majority as a bulwark against the increasing prospect of a Democrat-run House. Online political journal The Cook Political Report expects Democrats to make a net gain of 25-40 seats as of this writing.
Democrats lead the early voting with 41 percent of the total turnout statewide to 38 percent for Republicans.
Secretary of State Mike Pompeo said in an interview with CBS' "Face the Nation" that the president's moves had nothing to do with electoral politics.
The White House did not reveal for whom the Trumps cast ballots. New York's Democratic Gov. Andrew Cuomo is facing Republican Marc Molinaro in the governor's race. If Republicans win 24 of those 34 seats - assuming everything else went to form - they'll keep the House.
Christopher Galdieri, an assistant professor at Saint Anselm College, said Democrats "have been fired up about 2018 since shortly after the 2016 election".
Trump is not on any ballot Tuesday, but has often said his policies and assessment of his 22-month White House performance are at stake, as US voters elect all 435 members of the House of Representatives and a third of the 100-member Senate.
"A Republican Congress means more jobs and less crime", he said. "Democrats let him stay". "That should be a solid Republican seat". Another 15 seats are "likely Democratic", where Democrats have at least a 75 chance of winning.
One spot, titled "Murder, Gangs, Terrorism", attacks Democrat Ron DiNicola, a Marine veteran and lawyer running against GOP Rep. Mike Kelly in a conservative-learning Pennsylvania district, for representing "a Mexican drug lord who tortured and murdered a USA agent". "I don't think it's going to happen", Zeleny added.
Trump's aggressive travel schedule over the next several days is aimed at boosting GOP Senate candidates as the party tries to expand its Senate majority, rather than working to defend embattled Republicans in the House, where the party's control appears in doubt.
On Wednesday, President Donald Trump managed to condense his anti-immigrant fear-mongering ahead of the November 6 midterms into a single, 51-second advertisement, which even some on the right are immediately decrying as "racist".
Democratic incumbent Heidi Heitkamp trails Kevin Cramer, her Republican challenger, by about nine points in North Dakota.
"I've talked to even some elected (Republican) officials who are kind of upset with the way things are and feel that Scott (Perry) is a little too extreme in some of his positions", Nickol said. The share of Democrats saying immigration is a top issue has dropped from 23 percent to 11 percent.
The most disheartening aspect of the entire episode was Trump's utter incapacity as a national leader. This election is about prosperity, Trump said.
But in order to make changes moving forward, Democrats must do more than just take back the House, they must do well in gubernatorial races and in the battle for state legislatures across the country.
Former President Barack Obama's national campaign tour to boost Democratic candidates takes an unusual path Sunday with an IN rally for Sen.
Trump campaigned for Braun on Friday and is heading back to the midwestern state for another Braun rally on Monday. The Democrats have blasted Trump's stance on illegal immigration, and many voters on the progressive left disapprove of Trump's stance.
According to two sources close to the House Intelligence Committee, who requested anonymity to speak freely about post-election plans, Democrats plan to focus a significant amount of energy on reopening the panel's now-shuttered investigation into Russian interference in the 2016 election, and whether members of the Trump campaign colluded with Moscow to tilt the race in his favour.
"It will be a very exciting five days", Trump said at the White House before departing on the Marine One helicopter.
Throughout the campaign, Trump has been tested out other explanations - pointing to historical headwinds for the party of an incumbent president and complaining about a rash of GOP retirements this year.