In addition, Trump attempted to cast the midterms as "the election of caravans, Kavanaugh, law and order and common sense" during a rally last week, a reference to a caravan of Honduran immigrants heading toward the USA border seeking asylum and Democratic opposition to Supreme Court Justice Brett Kavanaugh, whom Trump successfully nominated.
An internal memo from White House director of political affairs Bill Stepien suggests Trump's team is making preparations to explain away a Republican loss of the House and position Trump to claim credit if the party holds onto control of the Senate or even expands its margin. Democrats are motivated to vote, and they're motivated to donate, the latter level of enthusiasm the GOP has yet to match this cycle, and at this point, the money race is over.
"It will be a sprint to the finish of the midterms for President Trump who is campaigning hard for GOP House and Senate campaigns across the map", Michael Glassner, the chief operating officer of Trump's reelection effort, said in a statement. In the months leading up to October, Republicans have largely lagged in ballot polls until recently as voters have "come home" following the Kavanaugh allegations.
"You need a wave where all the toss-ups essentially go one direction and then Democrats need to pick up two more seats to get a majority".
What will Democrats win in Senate and House mean for Trump?
If the Democrats do take a majority, Mr Trump may struggle to push through any major legislative victories in the last two years of his first term.
Some Republicans deep in Trump country have regained ground.
Many incumbent Republican House members have chosen not to stand and contest their seats in November.
Some of these seats are in key swing states such as Florida and Pennsylvania.