Donald Trump says he plans to spend more than $400m to help Republican candidates win the November 3 midterm elections.

He announced the figure on Truth Social and said more than $300m of it had already been spent.

He listed ads, voter contact, rallies, telerallies, get-out-the-vote programmes and election integrity work, but gave no breakdown by race.

Trump called it a great honour to spend the money and said this was the most important midterm election in the country's history.

Republicans face headwinds, including pushback over the economy and the long US-Israeli war against Iran.

A Reuters/Ipsos poll this week found only 31 percent of Americans approved of Trump's job performance.

Some Republicans have kept their distance from the president. Others in close races have asked him for more money.

His super PAC, MAGA Inc, entered September with $415.8m in cash. By law, its spending must stay independent of candidates' campaigns.

Last month the Campaign Legal Center, a watchdog, accused Trump of breaking those rules by claiming control over MAGA Inc's spending.

Elon Musk has reportedly spent $366m since last year on Republican campaigns through America PAC and other groups.

Republicans hold slim majorities in both chambers. Democrats hope to flip the House and Senate and block much of Trump's agenda.

Read the full article for more on the spending and the race for Congress.