Former New York City mayor Michael Bloomberg is committing at least 100 million US dollars to help Joe Biden’s presidential campaign in the crucial battleground state of Florida.

Mr Bloomberg’s late stage infusion of cash reflects Democrats’ concerns about the tight race in a state that is a priority for President Donald Trump.

A victory for Mr Biden in Florida, the largest of the perennial battleground states, would significantly complicate Mr Trump’s path to reaching the 270 Electoral College votes needed to secure a second term.

The billionaire Mr Bloomberg launched his own campaign for the Democratic nomination late last year amid worries about Mr Biden’s strengths.

Despite spending one billion US dollars on his campaign, Mr Bloomberg struggled and dropped out in March, quickly endorsing Mr Biden.

Mr Bloomberg’s new spending is intended to boost Mr Biden before the start of early voting in Florida, which begins on September 24.

A Bloomberg adviser said much of the money will go to television and digital advertising.