Trump’s presidency may be at stake if Democrats reclaim the House in the midterm elections and gain ability to thwart his agenda

Donald Trump delivered his closing argument on Monday, embarking on a three-stop tour of the midwest before the most consequential midterm elections in a generation.

Continuing an approach established in recent weeks, the president used campaign rallies, his Twitter account and press interviews to warn of an “invasion” by a caravan of migrants approaching the southern border, and of the supposed threat posed by “leftwing mobs”.

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It was an effort to energize his conservative base in the final days of an election season roiled by fear, division and racial anxiety which reportedly left the House speaker, Paul Ryan, pleading with Trump to focus on the roaring economy instead. According to the website Politico, the president demurred.

Trump’s presidency may be at stake. If Democrats reclaim the House, as they are favored to do and party leadership has said it expects, they will be empowered to thwart his agenda. If Republicans maintain control of the House as well as the Senate, their expected prize, they could be emboldened to press home Trump’s policies.

As Barack Obama delivered his own closing arguments against Trump – telling Democrats in Virginia “the character of this country is on the ballot, who we are is on the ballot” – the president spent Monday morning tweeting endorsements of Republicans, before moving on to rallies in Ohio, Indiana and Missouri. He also reprised his baseless claim of widespread voter fraud.

Donald J. Trump (@realDonaldTrump) Law Enforcement has been strongly notified to watch closely for any ILLEGAL VOTING which may take place in Tuesday’s Election (or Early Voting). Anyone caught will be subject to the Maximum Criminal Penalties allowed by law. Thank you!

“Law Enforcement has been strongly notified to watch closely for any ILLEGAL VOTING which may take place in Tuesday’s Election (or Early Voting),” Trump tweeted. “Anyone caught will be subject to the Maximum Criminal Penalties allowed by law. Thank you!”

The issue has flared up in Georgia, where the secretary of state, Brian Kemp, who is also the Republican gubernatorial candidate, oversaw a purge of more than half a million voters from the state’s rolls. Democrats and civil rights groups have called this voter suppression in one of the most closely watched governor’s races. Kemp has denied the charge.

Play Video 1:52 Obama v Trump: contrasting pitches as midterms loom – video

Over the weekend, Kemp announced an unexplained investigation into alleged “cybercrime” by the Georgia Democratic party. The Democratic candidate for governor, Stacey Abrams, said on Monday her opponent had “abused his power”. If elected, Abrams would be the first non-white, non-male governor of Georgia and the first female African American governor in US history.

The justice department announced it would send personnel to 35 jurisdictions in 19 states to “monitor compliance with the federal voting rights laws”.

Across the US, campaigns were making their final pitches amid reports of sky-high enthusiasm and record turnout among early voters.

According to new polling from NextGen America, a liberal advocacy group led by the billionaire Tom Steyer, youth turnout in the midterms is expected to surge. Turnout among 18- to 35-year-olds traditionally lags behind other age groups, a gap that grows wider during midterms. But data shared with the Guardian suggested this year may be different. Among such voters in six key states, 37% said they would definitely vote or had already voted. In the 2014 midterms, only 23% voted.

The data indicated that such voters lean heavily Democratic, preferring a Democrat to a Republican on a generic ballot by 59% to 33%.

Trump has made the midterms a referendum on his presidency. Though he has happily claimed credit for the humming economy and positive employment figures, he has forced immigration, race and nationalism to the fore. At a campaign rally last month, he declared himself a “nationalist”.

Play Video 2:43 What are the US midterms and why do they matter? – video explainer

On Monday he also returned to another familiar target: the media. In a tweet, Trump appeared to make the argument that public opinion polling, which has consistently forecast a Democratic takeover in the House, was intended to suppress Republican turnout.

'A new cultural era': midterms see firsts as candidates poised to make history Read more

“So funny to see the CNN Fake Suppression Polls and false rhetoric” Trump tweeted. “Watch for real results Tuesday. We are lucky CNN’s ratings are so low. 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!”

However, most such polling predicted Trump would lose the presidency to Hillary Clinton in 2016, only for a string of wins in post-industrial, rust belt states to hand him the White House via the electoral college.

On Monday, Trump was scheduled to travel back to some such areas. He would fly to Cleveland, to campaign for Republican gubernatorial candidate Mike DeWine. He was then due in Fort Wayne, Indiana, to campaign for the Republican Senate candidate Mike Braun, who is trying to unseat Democrat Joe Donnelly.

Trump was to end the day in Cape Girardeau, Missouri, with a rally for Republican Josh Hawley, the state attorney general who is mounting a strong challenge to the Democratic senator Claire McCaskill.

As Trump prepared to leave Washington, the weather turned against him. The president was grounded, forced to travel from the White House to Joint Base Andrews in Maryland by motorcade, instead of flying high on Marine One.