In the last weekend before the pivotal midterm elections, US President Donald Trump has made a final pitch to voters in hopes of keeping Republicans in control of Congress.

Trump held rallies in Florida, Iowa and Kansas - states he won in past elections - in a sign of Republicans' defensive stance ahead of Tuesday's vote.

Facing voter frustration over rising prices, Trump sought to tamp down such concerns and shift focus on attacking Democrats, saying they would "bankrupt" families if elected.

Polls suggest that Democrats have a good chance at winning at least partial control of Congress, which would act as a check on Trump's power and could upend the last two years of his presidency.

Trump has been campaigning non-stop across the country ahead of the election - even in areas that were once thought to be safe Republican strongholds.

Throughout the weekend, Trump made the case for his party at rallies in Kansas, Florida and Iowa as well as at tele-rallies for candidates in states including Michigan, Ohio and Pennsylvania.

In previous years, Trump easily won Florida, Iowa and Kansas - once considered reliably Republican states - but the president's visits there in the final days of his election drive highlighted just how competitive these states have become in determining control of Congress.

'I've had people eating cat food': Rising cost of living top of mind for US voters

Trump told supporters he had transformed the country, saying Democrats had left the US in a "dark age" but under his command, "we quickly turned it into the golden age of America".

Trump is facing a backlash over the cost of living. Prices have gone up, particularly for fuel, groceries and health care, since the war in Iran began over eight months ago. At these rallies, Trump appeared to have two aims: to change the subject from those issues and use fear to turn out the Republican vote.

At rallies in Florida and Iowa, he highlighted his policies on trade and immigration and said if Democrats were given power, they would "open the border", "bankrupt your family", "take away your guns" and "mutilate your children". He played video montages of Democrats criticising ICE and supporting transgender rights.

In the room at the rallies, supporters cheered, but there has also been disquiet among some Republicans over Trump's appeal with more moderate voters.

Democratic House leader Hakeem Jeffries said this weekend that he was "very confident" his party was on course to win control of the House of Representatives, as senior Democrats including former President Barack Obama made final appeals to voters.

A forecasting tool from Harvard University that analyses and compiles multiple polls and historical data suggests that Democrats have a 96% chance of taking the House and a 76% chance of taking the Senate.

Democrats have high hopes for midterms, but polls have let them down before

Four investigations Democrats could launch if they win control of Congress

A national poll from NBC News posted this weekend suggests that registered voters prefer a Democrat-controlled Congress by a 7-point margin, leading Republicans 52% to 45%.

But along with the last-push campaign stops, this weekend featured a dramatic turn in the Senate race in Michigan - a tightly contested seat currently held by Democrats.

Haley Stevens, a sitting congresswoman who lost the Democratic Senate nomination to Abdul El-Sayed, endorsed Republican candidate Mike Rogers on Sunday.

The move led to widespread condemnation from fellow Democrats and praise from Republicans, including Trump who called her "very brave".

In Alaska, home to another crucial Senate race, a judge on Sunday dismissed an attempt by the Trump administration to delay certifying election results if the Republican incumbent candidate loses due to two candidates appearing on the ballot with the same name.

Democrat endorses Republican candidate in key Michigan Senate race as party spat erupts

Judge dismisses Trump administration's lawsuit over two Dan Sullivans in Alaska election

Trump says US voter fraud is 'rampant' - evidence suggests it is extremely rare

In the lead up to the election, Trump and his administration have repeatedly cast doubt on both the credibility and security of the vote, despite evidence showing voter fraud is rare. The justice department has launched investigations or demanded votes be set aside in multiple US states.

The stakes are high for Trump, as midterm election results are seen as a measure of how satisfied Americans are with a president's performance.

In most midterm elections, the party that holds the White House typically loses seats in Congress to the opposing party - meaning Trump's Republican party has the most to lose.

Republicans, who currently hold a slim majority in both the House of Representatives and Senate, don't want to relinquish their party's majority in Congress, as losing any seats would hinder their ability to pass laws and shape policies.

Democrats, however, are keen to gain control from Republicans. Holding a majority would enable them to challenge Trump's agenda, give them investigative powers over his administration, and could also help them showcase their vision for America ahead of the 2028 presidential election.

For lawmakers, it's all about gaining or maintaining power and control, but it's Americans who will feel the impacts of their policies.

Who gets elected at the city, state, and federal level affects many aspects of voters' everyday lives, including the cost of gas, rising inflation and grocery prices, healthcare and abortion access, income and property taxes, and immigration.

EXPLAINED: Why Trump's approval rating matters in the midterms

IN DEPTH: The Republicans walking a Trump tightrope

RESULTS: Who will win the midterms? How the US elections will be won and lost

Alaska governor orders probe into Democratic campaign's alleged links to same-name candidate

Judge dismisses Trump administration's lawsuit over two Dan Sullivans in Alaska election

'The necktie is dead': How US midterm candidates are dressing for votes