John Kasich is to suspend his presidential campaign in the US, leaving Donald Trump the sole Republican candidate still standing. The Ohio governor will formally announce he is to step down from the campaign at a rescheduled press conference in Columbus, Ohio.

The decision from Kasich arrived after fellow Republican candidate Ted Cruz also announced he is dropping out of the race, following a crushing defeat to Trump in Indiana that all but secured the billionaire tycoon as the Republican candidate for the US presidency.

Kasich's campaign team said in a press update: "Today's [4 May] press gaggle in Dulles has been cancelled. Governor Kasich will deliver a statement in Columbus at 5pm EDT [9pm GMT] today – location TBD."

NBC News first reported that Kasich was to stand down, with the news later confirmed by three campaign officials who spoke to the Associated Press on the condition of anonymity.

Trump was already declared the "presumptive" GOP nominee by Republican Party chairman Reince Priebus after Cruz stood down. Priebus added the party now must "unite and focus on defeating" predicted Democrat nominee Clinton.

Kasich, who like Cruz was mathematically eliminated from winning the nomination outright, stepped down after only winning one primary, in his hometown of Ohio. Before the news he was going to step down broke, he issued a Luke Skywalker-themed press release for Star Wars Day (4 May) suggesting "our only hope" for stopping Trump from losing in the biggest electoral landslide since 1984 against Clinton was to vote for him.

According to NBC News, Kasich was only able to amass 154 delegates during his campaign, behind Marco Rubio's 172 delegates, who had dropped out back in March.