Story highlights

Ohio Gov. John Kasich has a narrow edge over Donald Trump in his home state's Republican presidential race, a new Monmouth University poll shows

Hillary Clinton, meanwhile, continues to lead Democratic rival Bernie Sanders by 14 percentage points

Columbus, Ohio CNN  — 

Ohio Gov. John Kasich has a narrow edge over Donald Trump in his home state’s Republican presidential race, a new Monmouth University poll shows.

Hillary Clinton, meanwhile, continues to lead Democratic rival Bernie Sanders by 14 percentage points – 54%-40% – in the Buckeye State, the poll shows.

Ohio will be a key battleground on Tuesday, when it and four other big states – Florida, Illinois, North Carolina and Missouri – hold primary contests.

READ: 6 takeaways from the Democratic town hall

On the Republican side, its 66 delegates are winner-take-all – and must-win for Kasich’s struggling campaign. He tops Trump, 40% to 35%, in the Monmouth poll.

Texas Sen. Ted Cruz and Florida Sen. Marco Rubio are both well behind. Cruz has 15% support, while Rubio has 5%.

What won’t hurt Trump: Friday night’s chaotic clashes between protesters and supporters in Chicago.

READ: Trump ends day on campaign trail by calling for protesters’ arrests

The survey found that 67% of Republicans said that will have no impact at all on their vote, while 16% said it makes them more likely to support Trump, and just 14% said it makes them less likely to do so.

The poll found relatively few late deciders. Just 8% of those surveyed said they’d already voted early, while 45% said they’re completely decided on a candidate and 29% have a strong preference. Just 8% have only a slight preference, while 11% are undecided.

READ: What are each candidate’s odds?

Among Democrats, Clinton’s double-digit lead indicates that she might be able to stop Sanders from repeating his stunning win in Michigan last week.

And 12% of Democrats said they’d already voted early, while 43% are completely decided on a candidate. Another 22% have a strong preference, while 12% have just a slight preference for Clinton or Sanders and another 11% are completely undecided.

The poll was conducted March 11-13. It includes 503 likely Republican primary voters with a margin of error of plus or minus 4.4 percentage points, and 302 likely Democratic primary voters with a margin of error of 5.6 points.