DETROIT (REUTERS) - President Donald Trump's strategy for retaining power despite losing the US election is focused increasingly on persuading Republican legislators to intervene on his behalf in battleground states Democrat Joe Biden won, three people familiar with the effort said.

Having so far faced a string of losses in legal cases challenging the Nov 3 results, Mr Trump's lawyers are seeking to enlist fellow Republicans who control legislatures in Michigan and Pennsylvania, which went for Mr Trump in 2016 and for Mr Biden in 2020, the sources said.

Michigan's Republican House Speaker Lee Chatfield has said the person who wins the most votes will win the electoral votes of his state, where Mr Trump trails by more than 150,000 votes.

But Mr Chatfield and Michigan's Senate Majority Leader Mike Shirkey will on Friday (Nov 20) visit the White House at the president's request, a source in Michigan said, adding they were going to listen and see what Mr Trump had to say.

In the United States, a candidate becomes president by securing the most "electoral" votes rather than by winning a majority of the national popular vote.

Electors, allotted to the 50 states and the District of Columbia largely based on their population, are party loyalists who pledge to support the candidate who won the popular vote in their state.

Typically, a state certifies a slate of electors based on which candidate won the popular vote, as Mr Biden did in Michigan and Pennsylvania.

States have until Dec 8 to meet a "safe harbour" deadline for resolving election disputes and choosing the electors who will select the president. The electors will convene as a so-called "Electoral College" on Dec 14 to formally select the next president, who will take office on Jan 20.

Mr Trump's lawyers are seeking to take the power of appointing electors away from the governors and secretaries of state and give it to friendly state lawmakers from his party, saying the US Constitution gives legislatures the ultimate authority.

A person familiar with the campaign's legal strategy said it has become a "more targeted approach towards getting the legislators engaged."

As things stand, Mr Biden has captured 306 electoral votes nationwide to Trump's 232, well ahead of the 270 needed for victory.

Were the combined 36 electoral votes in Michigan and Pennsylvania to go to Mr Trump, he would trail by 270-268 electoral votes, meaning his campaign would still need to flip at least one more state to retain the White House.

A senior Mr Trump campaign official told Reuters its plan is to cast enough doubt on vote-counting in big, Democratic cities that Republican lawmakers will have little choice but to intercede.

The campaign is betting that many of those lawmakers, who come from districts Mr Trump won, will face a backlash from voters if they refuse to act. The campaign believes the longer they can drag this out, the more they will have an opportunity to persuade lawmakers to intervene, the official said.

A Reuters/Ipsos opinion poll published this week suggested the Trump campaign had succeeded in stirring doubt - however unfounded - about the presidential election. The survey found about half of Republicans think Mr Trump "rightfully won" the election he lost.

Uphill fight

Mr Trump faces an uphill fight. Officials have said repeatedly there is no evidence of widespread voting irregularities.

Legislators in Michigan and Pennsylvania have sought not to become involved. Several leading Republicans in Michigan privately express dismay at the extent to which Mr Trump has tried to game the election results, believing it will irreversibly tarnish the party's image in the state for years to come.

Part of the Trump campaign effort involves trying to delay certification, the normally routine process by which election results are finalised, either through recounts or by stalling at the local level, the campaign official said.

That happened on Tuesday in Detroit, Michigan, where Republican members of the Wayne County Board of Canvassers briefly refused to certify the results, citing small discrepancies in the number of votes. The Republicans reversed themselves after hours of heated public comment, only to say in affidavits late on Wednesday that they felt threatened and wanted to rescind the certification.

One of the Republicans, Ms Monica Palmer, said in an affidavit that the election in Wayne County "had serious process flaws which deserve investigation." She said she voted to approve the results because she thought the state would conduct an audit.

Ms Palmer told Reuters in a text on Thursday that Mr Trump called her after she voted to certify the results. She said "there was no discussion of an affidavit" during the call, but did not say whether the two discussed the certification vote in detail.

Mr Trump's campaign dropped a federal lawsuit on Thursday challenging the election results in Michigan, citing the Wayne County officials' affidavits.

But Ms Tracy Wimmer, a spokeswoman for Michigan's secretary of state, said it was too late for the Republicans to rescind their certification. "Their job is done," she said.

Asked at a news conference on Thursday about Mr Trump's outreach to Michigan officials, Mr Biden called it "outrageous" and added it was the latest evidence that Mr Trump is among the "most irresponsible presidents in American history."

"Most of the Republicans I've spoken to, including some governors, think this is debilitating. It sends a horrible message about who we are as a country," he said.

Mr Trump's lawyers already have implemented the strategy in a lawsuit seeking to overturn the results of Pennsylvania, where Mr Trump trails by 82,000 votes.

In a court filing on Wednesday, his lawyers said they would ask a federal judge to either block the state from certifying the results or to declare that they were "defective" and allow the state's Republican-led legislature to choose its own slate of electors.

Mr Trump's effort to enlist state lawmakers emerged after the president turned his legal efforts over to his personal lawyer, Mr Rudy Giuliani, a person familiar with the effort said.

Mr Trump, the person said, "didn't like the results and he put a guy in he knows and trusts, emulates his style."

Asked at a news conference on Thursday if the campaign's aim was to block state certifications so Republican lawmakers could pick electors, Mr Giuliani laughed and said the goal was to get around what he called an "outrageous iron curtain of censorship."

Election officials and experts believe the Trump campaign has little chance of success.

"The results in Michigan and Pennsylvania are not particularly close, and the Trump campaign has come forth with no facts or legal theory that would justify disenfranchising hundreds of thousands of voters or throwing out the election results," said Mr Rick Hasen, an expert on election law at the University of California, Irvine, School of Law.

"This is a dangerous though almost certainly ineffective attempt to thwart the will of the voters or to delegitimise a Biden presidency based upon false claims of a stolen election," he said.