For Donald Trump, his path to the White House in 2016 was simple: promise action on immigration, the economy and repealing his predecessor's flagship healthcare policy, Obamacare.

The playbook for the midterms – despite the White House not being at stake – is the same. Mr Trump knows what the type of promises and rhetoric that he believes will bring his supporters to the polls and he has been hitting it hard over the past few weeks.

With Mr Trump’s Republican Party currently holding both sides of Congress, the House of Representatives and the Senate, his administration should be in the best position to push through his agenda. The president knows that if the Democrats take control of one of the chambers – and he has recently admitted that they could take the House in the midterms – it will make the second half of his presidency harder.

By Friday night, more than 32 million people had cast their votes for the midterms early according to The Election Project at the University of Florida, which tracks turnout. That is up more than 50 per cent from the 20.5 million early votes cast in all of the 2014 midterms. Mr Trump’s words have power, and his plan is for his supporters to spearhead a high turnout, whether that is voting early or on election day on 6 November.

The president’ rhetoric this week has concentrated on immigration, and it has brought out the worst traits. The caravans of thousands of refugees and migrants – many of them fleeing violence in Central America – currently making their way slowly through Mexico towards the US border have been the main target.

Without citing any evidence, Mr Trump has claimed the caravans are full of “Middle Easterners” and “criminals”. The language is similar to what he used in 2016, which allows him to push his hardline agenda on immigration.

US midterm elections: the voters Show all 10 1 /10 US midterm elections: the voters US midterm elections: the voters Ross Kershey of Exton, Pennsylvania objects to President Trump's recent threat to unilaterally suspend the constitutional protection of birthright citizenship as a way to control undocumented immigrants AP US midterm elections: the voters Thomas Jakel of Eveleth Minnesota is a former miner. The economy is the most important thing to voters in his town AFP/Getty US midterm elections: the voters Jerry Mcneff of Exton, Pennsylvania intends to split his ballot between the parties for Pennsylvania's House, Senate and governor elections AP US midterm elections: the voters Jean Hoffman of Exton, Pennsylvania has concerns about the cost of her daughters' college education. She thinks that voting Republican might help extend the economy's rise AP US midterm elections: the voters Supporters attend a rally of President Trump in Rochester, Minnesota AFP/Getty US midterm elections: the voters Supporters attend a rally of President Trump in Rochester, Minnesota Reuters US midterm elections: the voters Supporter Jenny Haley and son wait in line to see a Trump Rally in Rochester, Minnesota AFP/Getty US midterm elections: the voters Dick Calef of Exton, Pennsylvania is a life-long Republican. He credits the economic gains in suburban Philadelphia to longer-term factors beyond Trump's policies, such as the growth of internet and health care companies. He's not yet sure how he will vote AP US midterm elections: the voters Markus Fasel of Mendota Heights, Minnesota attends a campaign event for Democrat Angie Craig, his favoured congressional candidate AFP/Getty US midterm elections: the voters Supporters attend a rally of President Trump in Rochester, Minnesota Reuters

Alongside that rhetoric, repeated at "Make America Great Again" rallies across the country, the president has also tweeted a video described as one of the most racist political adverts in recent years and an attempt to rally his base by portraying Central American migrants as police killers set to overrun the country.

The advert – which Mr Trump tweeted with the message “it is outrageous what the Democrats are doing to our country. Vote Republican now” – focusses on Luis Bracamontes, an illegal immigrant twice previously deported, who in 2014 shot and killed two California police officers, and injured a third. The advert shows Bracamontes, who has been sentenced to death, laughing in court and vowing to kill more officers.

Words across the screen read: “Democrats let him into our country. Democrats let him stay.” It then shows migrants pulling on what appears to be a border fence.

Donald Trump says stone-throwing migrants could be shot by US military

The advert, which many have likened to the notorious “Willie Horton” attack advert that was used by Republicans to undermine and derail the 1988 presidential run of Democrat Michael Dukakis, has been widely denounced as racist, seeking as it does, to compare all migrants to a police killer.

The president has announced that he will send up to 15,000 troops to the border to meet the migrant caravans as they arrive – even suggesting on Thursday that any migrants illegally crossing the border and throwing stones at the military would be treated as if that stone was a rifle, and potentially being shot.

Mr Trump has also claimed that he will put out new executive orders next week aimed at ending birthright citizenship – the right for all babies born in the US to be called US citizens regardless of parentage, which is enshrined in the Constitution – and some rights of asylum seekers.

No doubt both of these will be challenged in the courts – if they arrive – as it is unclear if Mr Trump has the legal basis for changing them without it going through Congress. These statements are part of more than 1,000 potentially misleading, false or exaggerated statements that Mr Trump has made in the past seven weeks, according to an analysis from The Washington Post.

Leading Democrats have picked up on this, with former president Barack Obama lamenting the fact at a rally of his own on Friday. ”When words don’t mean anything, when truth doesn’t matter, when people can just lie with abandon, democracy can’t work,” Mr Obama said.

Barack Obama: 'we have seen repeated attempts to divide us with rhetoric designed to make us angry and make us fearful'

His former vice president, Joe Biden, picked up the baton in Ohio on Saturday. “We're in a battle for America's soul,” Mr Biden told a crowd at a high school south of Cleveland. “We Democrats have to make it clear who we are. We choose hope over fear, we choose unity over division, we choose our allies over our enemies and we choose truth over lies.”

It appears that even Mr Trump's team has realised he may be going too far, with some Republicans preferring that the president concentrates on the positive news about the economy rather than immigration.

First Mr Trump walked back his remarks about using force against migrants on Friday, and later he appeared to try to explain why he had not been touting US economic success so heavily recently.

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“Sometimes it's not as exciting to talk about the economy because we have a lot of other things to talk about,” Mr Trump said during a rally in West Virginia. He then said America was “booming” at a rally in Montana.

Mr Trump's rally schedule ahead of Tuesday's midterms will take in Montana, Florida, Georgia, Tennessee, Ohio, Indiana and Missouri, and he is focusing on rural areas where his supporters are concentrated. However, his hardline, nationalist “America First” agenda that plays so well to his supporters does not do the same in suburban areas where Republicans are in tough House races.