US president-elect Joe Biden’s victory in Arizona has expanded his electoral vote margin, placing any hopes of Donald Trump reversing the outcome even further out of reach.

Mr Biden was projected to win Arizona and its 11 electoral votes on Thursday (local time) after more than a week of vote counting from the November 3 election, Edison Research said.

Edison Research has also projected Mr Biden defeated Mr Trump in Georgia while Mr Trump won in North Carolina, making the Electoral College votes 306 for Mr Biden and 232 for Mr Trump.

Mr Biden becomes only the second Democratic presidential candidate in seven decades to win Arizona, traditionally Republican state.

To win a second term, Mr Trump would need to overturn Mr Biden’s lead in at least three states but he has so far failed to produce evidence that he could do so in any of them.

States face a December 8 “safe harbour” deadline to certify their elections and choose electors for the Electoral College, which will officially select the new president on December 14.

In Michigan, where Mr Biden won by 2.6 percentage points or more than 148,000 votes, two Republican state senators have asked the state’s top election officials to audit the results before certifying them.

They cited a “glitch” in vote-counting software, allegations that ballots were mishandled and impediments to poll-watchers.

“These claims deserve our full attention and diligent investigation to ensure fairness and transparency in our election process,” Lana Theis and Tom Barrett said in a letter to Secretary of State Jocelyn Benson.

The state has said that the canvassing process, which is a county-by-county review of the vote count, is in itself an audit.

Mr Biden’s legal advisers have dismissed the Mr Trump lawsuits as political theatre.