2020欧洲杯官方网站A third of the Democratic delegates will be decided in Tuesday's primaries and a caucus.

For Democratic presidential candidates, the Super Tuesday primaries send a clear message: win, or at least exceed expectations, or go home.

2020欧洲杯官方网站Two local political science professors say that will narrow the field in the nomination contest.

"It's the first real day when there will be a winnowing out of the field," said Paul Watanabe, of Weymouth, a political science professor at the University of Massachusetts at Boston. "It's not so much what will happen in Massachusetts, it's Massachusetts and the rest of the states. We will know by March 4th if this thing is clearly muddled, or if there is a clear path for one or two candidates."

2020欧洲杯官方网站A third of the delegates to July's Democratic National Convention in Milwaukee, 1,344 in all, will be awarded in the 14 primaries and one caucus Tuesday. Among them are the big prizes of California, with 415 delegates, and Texas, with 228 delegates, along with Massachusetts, which has 91 delegates. A candidate needs 1,991 delegates to win the nomination on the first ballot.

2020欧洲杯官方网站Brian Frederick, who chairs the political science department at Bridgewater State University, also thinks there will be a smaller group of candidates after Tuesday.

"It could be down to Bloomberg, Biden and Sanders as the three main contenders," he said.

2020欧洲杯官方网站It seems there are more story lines than candidates in the Democratic field that will be developed by Tuesday's results.

2020欧洲杯官方网站Can Vermont Sen. Bernie Sanders retain the front-runner status he gained in the early voting? Can former Vice President Joe Biden regain momentum after poor performances in the early states? What impact will former New York Mayor Mike Bloomberg have on the race after appearing on ballots for the first time? Can Massachusetts Sen. Elizabeth Warren and Minnesota Sen. Amy Klobuchar top the ticket in their home states and make strong showings elsewhere? And can Pete Buttigieg position himself as the moderate alternative to Sanders?

2020欧洲杯官方网站The polls in Massachusetts will be open from 7 a.m. to 8 p.m. Tuesday.

2020欧洲杯官方网站There is also a Republican primary in Massachusetts, along with ones for the Libertarian and Green-Rainbow parties. Voters who are not enrolled in a party may take any ballot. Those who are registered as party members must take that party's ballot.

Frederick points out that Sanders scheduled two rallies in Massachusetts before the primary, one in Springfield on Friday night and another at noon Saturday on Boston Common.

"That's a pretty bold statement," Frederick said. "That signifies he thinks he can win."

2020欧洲杯官方网站If Sanders wins in Massachusetts, Warren's campaign may end, he said.

"If she can't win her home state, I can't see how she goes on," Frederick said.

2020欧洲杯官方网站In the 2016 primary, former Secretary of State Hillary Clinton beat Sanders by just over 17,000 votes in Massachusetts.

Frederick said Sanders did the best among voters under 50 in the early contests during this primary race.

"A lot of voters like him, but they don't think he can beat Trump," he said.

Sanders is the only candidate who has announced appearances in Massachusetts in the final push before the primary. In 2016, he held a primary-eve rally at Milton High School.

2020欧洲杯官方网站Frederick said the candidates are spending their time in states with more delegates.

But they are sending their surrogates to Massachusetts. For example, Klobuchar's husband, John Bessler, was expected to appear at a "Hotdish House Party" on Saturday morning in Hingham. The event gets its name from Klobuchar's signature casserole.

2020欧洲杯官方网站Mostly, the campaigns locally are concentrating on their ground games, door-to-door canvassing and phone banks.

2020欧洲杯官方网站Not to mention the airwaves, with a series of radio and television ads and interviews.

2020欧洲杯官方网站Watanabe notes there is one number to keep in mind when following the results of Tuesday's voting: 15 percent. That is the threshold candidates need to meet to qualify for delegates.

This is the first presidential primary with early voting in Massachusetts.

2020欧洲杯官方网站Voters will also select members of their party's state, town and ward committees.

On the Republican side, Watanabe doesn't expect former Massachusetts Gov. William Weld, of Canton, to have much of an impact given President Donald Trump's dominance of the party.

"If Weld gets 20 percent of the vote, I'd be surprised," Watanabe said. "Republicans don't really have a reason to come out and vote."

2020欧洲杯官方网站Other states voting on Tuesday are Alabama, Arkansas, Colorado, Maine, Minnesota, North Carolina, Oklahoma, Tennessee, Vermont and Virginia. There is a caucus in American Samoa.

Voters in South Carolina go to the polls Saturday. There are 54 delegates at stake in that state.

2020欧洲杯官方网站Another major set of primaries looms two weeks after Super Tuesday, in Arizona, Florida, Illinois and Ohio. A total of 577 delegates will be at stake.