Donald Trump was making his last plea to the American people on Monday, attending three rallies in Ohio, Indiana and Missouri just hours ahead of polls opening in crucial midterm elections.

With control of Congress at stake, former President Barack Obama was also out at an event in Fairfax, Virginia, to try and give the Democrats a boost.

Voters will go to the polls on Tuesday with all 435 seats of the House of Representatives up for re-election as well as 35 Senate seats, hundreds of state legislature, local mayoral races, and special ballot provisions.

Republicans currently control both the houses of the US congress, although Mr Trump has warned about what a change would mean or his agenda.

“It's all fragile. Everything I told you about, it can be undone and changed by the Democrats if they get in,” Mr Trump told supporters in a conference call.

He has also admitted Republicans could lose control of the lower House, but has not shown anything but his characteristic bombastic confidence at his numerous political rallies.

Some of the key races are also the most expensive in what is the most expensive overall election in US history, clocking at $5bn plus in spending.

In Texas, Democrat Beto O'Rourke and Republican incumbent Ted Cruz face off for a US Senate seat. In Florida there are two races of note: Republican Governor Rick Scott vies for a US Senate seat against Democrat Bill Nelson and Democratic Mayor of Tallahassee Andrew Gillum looks to become the state's first African-American governor against Republican Ron DeSantis.

In Georgia, Democrat Stacey Abrams looks to become the country's first African-American female governor as she runs against Republican Brian Kemp. Mr Kemp has been called to resign from his state government post of secretary of state since his office is tasked with monitoring elections, particularly should neither of them garner 50 per cent of the vote and a runoff occurs. Mr Kemp has been accused of voter suppression and is also investing Democrats over a possible cybersecurity vulnerability of the state's voter registration page they reported to his office.

Republican Mike DeWine was joined by the president in Ohio as he runs against a former director in Barack Obama's administration, Richard Cordray.

There are numerous tight House races across the Midwest as well. Democrats will need to pick up 24 more seats in order to "flip" control to them.

You can see how the events of the last day of campaigning before the midterms unfolded in our live blog below