Ohio Governor John Kasich has dropped out of the presidential race after struggling to gain traction against Republican front-runner Donald Trump, US media report.

Kasich did not have a path to secure the nomination outright, but pledged to lobby for his candidacy during the Republican convention in July.

Trump holds a commanding lead and is closing in on the nomination.

Despite being a popular governor, Kasich only won his home state.

Texas Senator Ted Cruz dropped out of the race on Tuesday after losing to Trump in the Indiana primary.

Kasich cancelled events in Washington and announced an evening event in his home state on Wednesday.

Earlier on Wednesday, he released a Star-Wars themed advert describing himself as the "only hope" against Donald Trump.

Kasich had been widely seen as the most moderate and electable Republican candidate and polled well against Hillary Trump, but that did not garner him enough support among Republican voters.

He promoted an optimistic message while campaigning, shunning negative attacks against other candidates.

Florida Senator Marco Rubio, who dropped out in March, garnered more delegates than him during primary elections.

Analysis - Anthony Zurcher, BBC North America reporter

The race for the Republican presidential nomination has taken more than a year to unfold, but in a flash it is over.

Ted Cruz's withdrawal from the race Tuesday night meant John Kasich's long-shot path to the nomination - deadlocked delegates in a contested convention turning to him as a compromise candidate - was definitively closed. The Ohio governor, once thought to be the saviour of the moderate, establishment wing of the Republican Party, could have soldiered on, but with little money and no hope of winning, such a course bordered on the absurd.

Although Trump had effectively sewn up the nomination regardless of what Kasich decided to do, his withdrawal does have one benefit. Now the New York businessman will not have to make even pro forma campaign stops in California, which holds its primary on 6 June.

Just last week the front-runner faced massive protests while attending the state's Republican convention. California looked to be a powder keg for Trump in the coming weeks. Thanks to Kasich, it has been defused.