President Joe Biden clinched a second straight Democratic nomination on Tuesday and set up an all-but-certain rematch with the predecessor he blames for destabilising the country.

Mr Biden became his party’s presumptive nominee when he won enough delegates in Georgia.

That pushed Biden’s count past 1,968 for a majority of delegates to the Democratic National Convention in Chicago this August, where his nomination will be made official.

Former President Donald Trump is expected to clinch the Republican nomination shortly.

Mr Biden, who mounted his first bid for president 37 years ago, did not face any serious Democratic challengers to his run for re-election at age 81.

That’s despite facing low approval ratings and a lack of voter enthusiasm for his presidency — driven in part by his age.

Just 38% of U.S. adults approve of how Mr Biden is handling his job as president while 61% disapprove, according to a recent survey by the Associated Press-NORC Center for Public Affairs Research.

Mr Biden and his allies are betting that over a bruising seven-and-a-half-month general election, his Democratic base and independent voters fearful of a second Trump presidency will stand with him despite their misgivings.

Their strategy to constantly highlight Trump’s perceived shortcomings – combined with Mr Trump’s plan to attack Biden in brutally personal terms — sets up a spiritless campaign that many Americans said they did not want but will have to decide in November anyway.

Mr Biden has tried to frame the race as a battle for freedom, both at home and abroad.

He contrasts his support for Ukraine and work to expand Nato with Mr Trump’s praise for Russian president Vladimir Putin and his suggestion that he would tell Russia to attack NATO allies he considers delinquent.