Donald Trump says he wants Republicans to "nationalise" US elections and has encouraged his party to "take over the voting" in at least some parts of the country.
The extraordinary comments appear to be part of a fresh push to undermine Americans' faith in the integrity of elections and seize power over the process.
The US Constitution empowers the states to prescribe "the times, places and manner of holding elections for senators and representatives", but says "Congress may at any time by law make or alter such regulations".
The US president made the comments on a conservative podcast hosted by former FBI deputy director Dan Bongino.
It was released just days after the FBI raided election offices in Atlanta, Georgia.
"The Republicans should say: 'We want to take over,'" Mr Trump said.
"We should take over the voting in at least, many, 15 places," he said, but did not identify those places.
"The Republicans ought to nationalise the voting."
Mr Trump has for years pushed unsubstantiated claims that he rightfully won the 2020 election which was actually won by Joe Biden.
Investigations and audits by federal, state and independent bodies do not support his claim, and courts rejected dozens of legal challenges by Mr Trump and his allies.
"We have states that are so crooked, and they're counting votes," Mr Trump told the podcast.
"We have states that I won that show I didn't win."
Democratic Senate leader Chuck Schumer said Mr Trump was "talking no differently than a dictator who wants elections in America to be as legitimate as elections in countries like Venezuela".
"Does Donald Trump need a copy of the constitution? What he's saying is outlandishly illegal," Senator Schumer said.
Republican Senate leader John Thune said he was also "not in favour of federalising elections".
"It's harder to hack 50 election systems than it is to hack one," he told reporters in Washington.
White House spokeswoman Karoline Leavitt later said Mr Trump's comments were actually about a proposed law to require voters to show identification.
"What the president was referring to is the SAVE Act, which is a huge common-sense piece of legislation" she said.
But when Mr Trump was asked to clarify his position soon afterwards, he did not mention that bill and said "the federal government should get involved" in running elections.
"If a state can't run an election, I think the people behind me should do something about it," he said, referring to Republican politicians who were standing with him in the Oval Office.
Trump thanked agents in FBI raids
Mr Trump's election conspiracy theories have largely centred on states like Georgia where Mr Biden enjoyed relatively narrow victories.
He said the public was "going to see some interesting things come out" after last week's raid in the state's biggest city, Atlanta, where FBI agents seized 2020 election ballots.
The raid has alarmed Democrats, who said it represented an attack on the non-partisan systems necessary for a strong democracy.
Democrats have also criticised the involvement of Mr Trump's director of national intelligence, Tulsi Gabbard.
Ms Gabbard this week confirmed she attended the raid. She also facilitated a phone call so Mr Trump could speak to the agents who carried it out.
Jim Himes, the top Democrat on the House of Representatives' intelligence committee, and Mark Warner, the vice-chairman of its Senate equivalent, have asked Ms Gabbard to front their committees for questioning.
In a joint letter, they wrote:
"It is also deeply concerning that you participated in this domestic law enforcement action. The Intelligence Community should be focused on foreign threats and, as you yourself have testified, when those intelligence authorities are turned inwards the results can be devastating for Americans' privacy and civil liberties."
In her response, which she posted on X, Ms Gabbard said she was at the raid "for a brief period of time".
"My presence was requested by the president and executed under my broad statutory authority to coordinate, integrate, and analyse intelligence related to election security," she wrote.
While at the raid she "thanked the FBI agents for their professionalism and great work, and facilitated a brief phone call for the president to thank the agents personally for their work", she wrote.
"He did not ask any questions, nor did he or I issue any directives."
Shortly after the 2020 election Mr Trump unsuccessfully lobbied Georgia's Republican secretary of state to help him "find 11,780 votes" to change the result in the state.
Mr Trump and many of his allies were later charged, accused of deploying a range of tactics to unlawfully change the outcome in the state.
The case was dismissed in November after a prosecutor said he would no longer pursue it.
