Want free tickets to the World Series? What about a trip to San Francisco to see a performance of the hit Broadway musical "Hamilton?"

You could be a lucky winner if you donate to a presidential candidate.

Democratic candidates working to raise campaign cash and rack up small-dollar donors have been offering free trips for months to those who chip in even small amounts to their campaigns. But the contests, which can elicit a spike in donations and help campaigns build their donor base, are getting increasingly elaborate as candidates jostle to stay afloat in the crowded field.

Giveaways can help campaigns build their email lists and boost the number of individuals donating to their campaign — a key metric that helps them meet increasing Democratic National Committee thresholds to earn a spot on the debate stage.

Two of the splashiest giveaways landed this week in offers from former Maryland congressman John Delaney and South Bend, Indiana, Mayor Pete Buttigieg.

Delaney, who has failed to gain popularity or make the stage in recent debates, is giving away a trip for two to join him in Washington for Game 4 of the World Series between the Houston Astros and Washington Nationals.

Delaney's campaign says the giveaway includes prime seats for Saturday's game, where the cheapest, standing-room-only seats are selling for more than $1,200 for those who aren't season-ticket holders.

Buttigieg, who has previously offered donors a chance to win a trip to his hometown and share a pizza, has upped his sweepstakes offers this week, promising to give away a trip to San Francisco for two to watch "Hamilton" with his husband, Chasten.

Other campaigns have been getting in on the action in recent months, albeit with less high-profile trips.

Former Vice President Joe Biden, former Texas Rep. Beto O'Rourke and tech entrepreneur Andrew Yang are among those who have offered free travel and hotels for donors to meet the candidate at Democratic debates. Massachusetts Sen. Elizabeth Warren offered to fly a donor somewhere to meet her for a drink or coffee, and New Jersey Sen. Cory Booker is offering a chance to dine with him and his girlfriend, actress Rosario Dawson.

Federal Election Commission rules say campaign funds can be used for travel expenses or admission to sporting events, theater performances and other entertainment if it's part of a specific campaign activity.

"The giveaways are treated as a fundraising expense, and that's what makes them permissible," said Adav Noti, senior director and chief of staff at the nonprofit Campaign Legal Center and a former lawyer for the FEC.

Yang announced during the September debate that he would use campaign funds to give $1,000 a month for a year to 10 random families to demonstrate the concept of the universal basic income, the cornerstone of his campaign. Yang has said the giveaway is legal, though Noti said it's "at best a gray area" because Yang wasn't offering it to donors, making it harder to justify giving away cash to random families as a fundraising expense.

Montana Gov. Steve Bullock, who has failed to make all but one debate and to break out of the pack, has criticized the giveaways as a gimmick. But he responded with an offer of his own, offering anyone to join him Friday night in Helena, Montana, to watch the Helena High School football team take on their local rivals.

"It's not Hamilton, it's not the World Series, and it's not free money, but this is real Friday Night Lights in small town America," Bullock said in a statement. "Everyone is welcome to join me in cheering on the #GoBengals as we wait for an explanation on how these gimmicks and giveaways are really going to help us beat Donald Trump. Hope to see you there!"

Obama ran regular "Dinner With Barack" contests during his 2008 and 2012 campaigns.

Bullock's campaign says they're not covering anyone's expenses, though the governor has offered to buy someone a Coke.

The contests are nothing new, said Tim Lim, a Democratic strategist who worked for Hillary Clinton's and Barack Obama's campaigns.

"These things are really popular. I think what you're seeing is just a bit more resources, energy and creativity put into the contests," Lim said.

Obama ran regular "Dinner With Barack" contests during his 2008 and 2012 campaigns. Like Buttigieg, Clinton raffled off tickets to see "Hamilton" during the 2016 race.

President Donald Trump, too, has offered a "Dinner with President Trump" sweepstakes.

Lim said the fundraisers are a popular fundraising tactic in the nonprofit world and a powerful way to get more from existing donors or those who haven't donated in a while.

For a contest like Delaney's offering tickets to a marquee event, the giveaway is likely to lure in those who may not be current donors but just want to see the World Series, Lim said, and may be unlikely to donate again.