Trump makes final push in US midterm elections

US President Donald Trump arrives for a 'Make America Great Again' campaign rally at McKenzie Arena, in Chattanooga, Tennessee. (Nicholas Kamm/AFP)

Cleveland, Ohio; Fort Wayne, Indiana; then Cape Girardeau, Missouri: it will be well after midnight before the real estate billionaire and populist showman gets back to the White House - and only a few hours more before polls open on Tuesday across the world's largest economy.

"Don't fall for the Suppression Game. Go out & VOTE. Remember, we now have perhaps the greatest Economy (JOBS) in the history of our Country!" he tweeted on Monday before setting off for the furious final round of campaigning. "With turnout predicted to spike compared to previous cycles, and US networks rolling out wall-to-wall coverage, Trump told a cheering crowd in Cleveland the media were "making a fortune" thanks to him and his supporters. "The midterm elections used to be, like, boring," he quipped. "Now it's like the hottest thing."

Trump is not on the ballot in the midterms, in which the entire House of Representatives and a third of the Senate are up for grabs.

But in a hard-driving series of rallies around the country the most polarising US president for decades has put himself at the centre of every issue.

With a characteristic mix of folksiness, bombast and sometimes cruel humor, he says voters must choose between his stewardship of a booming economy and what he claims would be the Democrats' extreme-left policies.

He leaned in to the theme of robust economic stewardship in a Fox News op-ed that said the US "has the best economy in the history of our country - and hope has finally returned to cities and towns across America."

But as he touched down in Indiana for the second leg of his tour, Trump was sanguine about the possibility of a Democratic victory in the House.

"We'll just have to work a little bit differently," he told reporters when asked how it would affect his presidency.

The bid to make it all about Trump is a gamble, as is his growing shift from touting economic successes to bitter - critics say racist - claims that the country is under attack from illegal immigration.

In the run-up to Tuesday's vote, Trump has sent thousands of soldiers to the Mexican border, suggested that illegal immigrants who throw stones should be shot, and told Americans that the Democrats would turn the country into a crime-and-drugs black hole.

But the angry tone has turned off swaths of Americans, giving Democrats confidence that they could capture at least the lower house of Congress, even if the Republicans are forecast to hold on to the Senate.

FIGHT FOR US SOUL

The Democrats rolled out their biggest gun in the final days of the campaign: former president Barack Obama, who on Sunday made a last-ditch appeal for an endangered Senate Democrat in Indiana.

Laying into the tangled legal scandals enveloping the Trump administration - especially the possible collusion between his presidential campaign and Russian operatives - Obama scoffed: "They've racked up enough indictments to fill a football team."

And describing the election as even more consequential than his own historic 2008 victory as the first non-white president, Obama said more than politics is at stake.

"The character of our country's on the ballot," he said.

The party of a first-term president tends to lose congressional seats in his first midterm. But a healthy economy favours the incumbent, so Trump may yet defy the historical pattern.

Although polls generally agree on Democrats winning the House and Republicans retaining the Senate, the margins are fine and a few key races will determine whether a real upset is on the cards.

One of those is Democrat Beto O'Rourke's challenge to Senator Ted Cruz in traditionally deep-Republican Texas.

On Monday, O'Rourke depicted the contest as an epic event, saying that Texans "will decide the election of our lifetimes. They will define the future, not just of Texas, but of this country, not just this generation but every generation that follows."

Other races to watch include Republican Pete Stauber's bid to flip a House Democratic stronghold in Minnesota, while Democrats in Florida and Georgia are aiming to become the states' first African American governors.

In the end, though, polls mean nothing if people don't actually vote, so even stormy weather forecast for Tuesday in much of the east of the country could end up having an impact.

VIOLENCE AND RHETORIC

Perhaps the biggest wild card is how voters will react to the increasingly extreme rhetoric and politically inspired violence in the last two weeks of the campaign.

In speeches, Trump has transformed a dwindling group of a few thousand impoverished Central Americans trying to walk to the United States into a ferocious threat.

This may work with Trump's ultra-loyal base. However, misgivings rose over the president's rhetoric after a Florida man and ardent Trump supporter was charged with sending homemade bombs to more than a dozen senior Democrats and other high profile opponents.

Just after, a gunman walked into a Pittsburgh synagogue and shot 11 worshippers dead.

He had allegedly lashed out online against Jews he accused of transporting Central American "invaders" into the United States - in language that echoed Trump's own attacks on the impoverished migrants as "an invasion."