But they also will be regarded as a verdict on the President's personal style, ranging from his language (welcome to some ears, intemperate to others), the symbolism he employs (refreshing to some eyes, racist to others), his bearing (bold to some minds, vulgar to others), his recasting of the country's political character (an overdue re-evaluation of US immigration policy to some, a rash of nativist fear to others), even his lifestyle (honest and unvarnished to some, tasteless and tawdry to others).
He repeated those themes in Georgia, urging voters to "look at what is marching up - that's an invasion". "And [voters are] going to say Republicans have offered a record of results and Democrats are offering resistance and going back".
"This election will decide whether we build on this extraordinary prosperity we have created", Trump said before cheering crowd in Macon, Georgia.
"If they take back the house, he essentially will become a lame-duck president, and he won't win re-election", said Amy Kremer, a Tea Party activist who leads the group, Women For Trump.
But the president - to the unease of some in the party - has instead used his almost nonstop schedule of campaign rallies to keep the spotlight on what he calls the security threat from migrants seeking to enter the USA through Mexico.
Trump is also telling reporters that Republican enthusiasm is off the charts and that the "level of fervor" is very high.
Another 28% say their vote isn't about the president. "I feel really good about things going into Tuesday".
And with a Democrat-controlled House, frustration could push more zealous Trump devotees into greater extremism against their adversaries, real or imagined.More news: Netanyahu refers to Saudi's regional power after Khashoggi murder
Democrats meantime insist that only they will protect the healthcare gains made under President Barack Obama, that Trump has employed inhumane measures to keep migrants out, and that the divisiveness he has fostered must end.
Among Republicans, just 33% think such interference is likely and 57% consider it a major problem or more.
"We're not letting these people invade our country", Trump declared.
As many as 74% say that the recent tone of American politics is encouraging violence among some people.
The Democrats' hopes of blunting the GOP's march or even flipping seats run through places such as Tennessee, where Mr. Bredesen is nipping at Ms. Blackburn's heels in the race to replace retiring Sen. But University of Saskatchewan public policy expert Daniel Béland, who has worked and studied in the US, says that ostensible trade continuity may be of little reassurance to business if it merely raises the ire of Trump and his supporters.
Tempers and emotions are at fever pitch all across the United States as President Donald Trump has worked hard to rouse passions, fears and insecurities of the people ahead of a crucial mid-term election that is being seen as a referendum on him. Those voters have increasingly fled Mr Trump's Republican Party, turned off by his chaotic leadership style and xenophobic rhetoric.
Republicans are bracing for a likely loss of seats in the House of Representatives but are favored to hold on to the Senate.
Turnout is expected to be high, with more than 34 million Americans already having voted in the election.
There may never have been a set of midterm contests with so many vital themes, so many contradictory impulses, so many contrasting campaign memes and so many reasons to doubt any predictions - some for blue wave for the Democrats, others for a red-wave backlash for the Republicans - about how Tuesday's 470 congressional races and 36 races for governors' chairs will turn out.