DOVER — After months of watching and listening to speculation, debate and even boasts about hand size, Delawareans get to finally take action in perhaps the wildest presidential election campaign in recent history. First State voters go to the polls Tuesday, along with four other states. Hundreds of polling locations will be open from 7 a.m. to 8 p.m. While Hillary Clinton appears to have the Democratic nomination just about sewn up, the state’s 16 Republican delegates could be crucial for GOP front-runner Donald Trump, whose rivals are fighting to prevent him from gaining the 1,237 needed to clinch the nomination before the national convention. Delaware Election Commissioner Elaine Manlove said she does not know what the turnout will be but is hoping the interest in this election results in a large number of people voting. “The ballot is what drives turnout,” she said. Delaware has a closed primary, meaning Democrats can only vote for Democrats and Republicans can only vote for Republicans. Technically, there are six Republicans on the ballot: Donald Trump, Sen. Ted Cruz of Texas, Ohio Gov. John Kasich, Sen. Marco Rubio of Florida, former Florida Gov. Jeb Bush and retired surgeon Ben Carson. However, the last three have suspended their campaigns, although because they have not formally submitted papers to withdraw, they can receive votes, Ms. Manlove said. On the Democratic side, former Secretary of State Hillary Clinton, Sen. Bernie Sanders of Vermont and businessman Roque De La Fuente will be the choices for voters. A poll conducted by the public relations firm Gravis Marketing earlier this month showed Mr. Trump winning in a landslide. The survey had him earning 55 percent of Republican votes, more than the other two candidates combined. Gov. Kasich had 18 percent, Sen. Cruz garnered 15 percent and 12 percent of the 1,038 respondents were undecided. On the Democratic side, Secretary Clinton received 45 percent of the voters, and Sen. Sanders got 38 percent. Seventeen percent of respondents were unsure of whom they would vote for. In total, 1,026 Democrats were polled. According to the company, 63 percent of Republicans described themselves as moderate or slightly conservative, while 67 percent of Democrats said they leaned toward the middle or slightly left. Though Gravis Marketing has been criticized for inaccurate polls, political observers say Mr. Trump is likely to win Delaware. A Sussex County Republican Party poll from about a month ago had Donald Trump crushing Sen. Cruz and Gov. Kasich, garnering 72 percent of the vote in total. Gov. Kasich’s own campaign believes the businessman will dominate in the First State. “We expect Trump to have a strong chance of finishing above 50 percent and would recommend spending resources on the other April 26th states,” chief campaign strategist John Weaver said in a mass email sent to the campaign’s mailing list. Because of Delaware’s small size, there are few polls focusing on the state. For years, the state’s primary was in February, but it was moved to April starting in 2012, going along with the wishes of the national parties. Because Delaware, Maryland, Pennsylvania, Connecticut and Rhode Island all go to the polls Tuesday, the day is sometimes known as the Acela Primary, a reference to the high-speed Amtrak rail that goes from Washington to Boston. About 16 percent of Delaware Republicans voted in the 2012 primary, which saw eventual GOP nominee Mitt Romney win the state. In 2008, 38 percent of Democrats and 28 percent of Republicans cast ballots, with eventual nominees Barack Obama and John McCain winning.

Delegates and campaigns

Delaware awards 16 delegates to the winner of the Republican primary, while the Democratic process is more complex. Twenty-one delegates are divided proportionally, and then 10 superdelegates, consisting of elected officials and party leaders, can choose who to support. Five of those superdelegates publicly have backed Ms. Clinton: Gov. Jack Markell, Sens. Tom Carper and Chris Coons, Rep. John Carney and former state House Speaker Robert Gilligan. Most of the delegates will be selected at the parties’ state conventions. The GOP meets April 30 in Dewey Beach, and the Democratic Party will do so April 7 in Dover. The 16 Republican delegates consist of a representative for each region (Northern New Castle, Western New Castle, Colonial, Kent and Sussex), eight at-large individuals, state party Chairman Charlie Copeland, National Committeeman Laird Stabler and National Committeewoman Ellen Barrosse. Attendees at the state Republican convention will vote on their entire slate of candidates as a whole, which is expected to be largely a formality. The Democratic delegation is made up of eight Democrats from rural New Castle, two from Kent, two from Sussex and two from Wilmington. There are also five at-large delegates and an additional two who are party leaders or elected officials. Aside from the Democratic superdelegates and the GOP chairman, national committeeman and national committeewoman, the identities of the delegates have not been revealed by the parties. The Delaware GOP, unlike some state parties, does not bind delegates to the winner of the popular vote beyond the first ballot. This means, should Mr. Trump fail to get the 1,237 delegates needed to clinch the party’s nomination, the July national convention could turn into a spectacle unlike few ever seen in American politics. Delegates from many states, including Delaware, will be free to switch their allegiance and back a different candidate. Many “never Trump” Republicans are clinging to this as the last hope, and both Gov. Kasich’s and Sen. Cruz’ campaigns have leaned on this option as the last chance to stop Mr. Trump. All of the candidates have opened offices in Delaware except for Sen. Cruz. With the notable exception of Mr. Trump’s Friday visit to Harrington, most of the efforts by campaigns have been concentrated on northern New Castle, the most populous part of the state. Sen. Sanders made a visit to Delaware Saturday, stopping by Wilmington for a rally, and Secretary Clinton is scheduled to meet with people in downtown Wilmington Monday. Through Friday, Delawareans had donated $537,340 to presidential candidates, with Secretary Clinton and Sen. Sanders receiving the most, according to the Federal Election Commission. Less than $6,000 had been donated to Mr. Trump, who has largely self-funded his campaign on his own personal wealth. Ms. Manlove, the election commissioner, said the primary costs a little less than $1 million to put on. Full results should be in by 9:30 p.m. Tuesday, about 90 minutes after the polls close. Major media outlets likely will begin calling the races earlier. There are about 312,000 registered Democrats and 185,000 registered Republicans in Delaware, according to the Department of Elections. For information, including eligibility and polling places, visit https://ivote.de.gov/.