The Ohio governor did not have a path to secure the nomination outright, but pledged to lobby for his candidacy during the Republican convention in July.
Donald Trump holds a commanding lead and is closing in on the nomination.
Despite being a popular governor, John Kasich only won his home state.
Texas Senator Ted Cruz dropped out of the race on May 3 after losing to Donald Trump in the Indiana primary.
John Kasich canceled events in Washington and announced an evening event in his home state on May 4.
Earlier, John Kasich released a Star-Wars themed advert describing himself as the “only hope” against Donald Trump.
Blocking from winning the nomination outright, John Kasich and Ted Cruz had hoped to force a contested convention, in which party officials, not voters, choose for the nominee.
Now it is all but certain Donald Trump will have the 1,237 delegates needed to become the nominee before the July convention in Cleveland, Ohio.
John Kasich had been widely seen as the most moderate and electable Republican candidate and polled well against Hillary Clinton, the likely Democratic nominee.
However, John Kasich’s general election strength did not garner him enough support among Republican primary voters.
The Ohio governor 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 John Kasich during primary elections.
Ted Cruz and John Kasich had announced an alliance to stop Donald Trump and “to ensure that we nominate a Republican who can unify the Republican Party and win in November” prior to the Indiana, New Mexico and Oregon state primaries, but that quickly crumbled.
Republicans are now divided over whether to support Donald Trump as the Republican nominee.
John Kasich’s name has been floated as a possible vice presidential pick but he has denied that he would accept a nomination.
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