'I put him down': Donald Trump is spending his election day attacking John Kasich on Twitter

Republican presidential frontrunner Donald Trump has attacked a long-shot rival throughout the day Tuesday, ahead of several major primary contests.

In a series of tweets, Trump tore into Ohio Gov. John Kasich over his support for the North Atlantic Free Trade Agreement, his stance on illegal immigration, and his losses in other state primaries and caucuses.

He also retweeted his son Eric, who said it would be impossible for Kasich to win the delegates he needs to secure the Republican nomination.

Trump is going after Kasich in the hours before Ohio voters cast their ballots in the state's winner-take-all primary. Sixty-six delegates are up for grabs. Florida, another big winner-take-all state with 99 delegates, also holds its primary on Tuesday, along with Illinois, Missouri, and North Carolina.

Trump is the clear frontrunner in the Republican race, but Kasich's campaign has been gathering steam. Recent polling in Ohio shows that the governor has a chance of beating Trump there, which could further the Kasich campaign's hopes for a contested convention in July.

Here's a look at what Trump was tweeting (and retweeting) on Tuesday:

Ohio and Florida are crucial for Trump's plan to wrap up the GOP nomination quickly, and he has invested a lot of his time in both states.

Politico noted that the two primaries "will determine whether there's chaos or a coronation at the Cleveland convention" in July. Top GOP operatives have reportedly been discussing the possibility of a contested convention, in which the nomination is decided on the convention floor.

Trump on the campaign trail:

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