(CNN) Vermont Sen. Bernie Sanders will beat Hillary Clinton in the Maine Democratic caucuses, while Florida Sen. Marco Rubio won the Republican primary in Puerto Rico.

Sanders' victory in Maine, which was announced during CNN's Democratic debate in Flint, Michigan , is his third of the weekend after winning Kansas and Nebraska.

For Rubio, it's his second contest in a campaign that has been dominated by Donald Trump and Texas Sen. Ted Cruz . With 100% of the votes counted on the island, Rubio topped the 50% threshold required to win all 23 of Puerto Rico's delegates.

The dominant issue facing the island commonwealth -- which has no electoral votes in the U.S. general election -- is a public debt crisis, with the government owing $73 billion.

What Puerto Rico results could mean

Puerto Rico's results are particularly key for Rubio, who campaigned there Saturday.

JUST WATCHED Marco Rubio projected to win Puerto Rico primary Replay More Videos ... MUST WATCH Marco Rubio projected to win Puerto Rico primary 01:26

But that stop wasn't just about Puerto Rico: Rubio's campaign now largely hinges on taking first place in Florida's March 15 99-delegate, winner-take-all primary -- and the state's Puerto Rican population could help there.

Rubio is trying to prevent Trump and Cruz from running away with the race. Through the first 19 contests, Trump has won 12 states and Cruz six -- including two each on Saturday. Rubio, meanwhile, had only won Minnesota before winning Puerto Rico. And Ohio Gov. John Kasich , whose state also holds a winner-take-all primary on March 15, is still seeking his first win.

Sanders had advantage in Maine

Sanders had an advantage in the state: He had already won in New Hampshire and Vermont, two nearby Northeastern states. He also racked up wins in two heavily white states -- Nebraska and Kansas -- on Saturday, though Clinton won in Louisiana.

Clinton and Sanders are squaring off Sunday night at a CNN Democratic debate in Flint, Michigan -- the site of a water crisis that has led both to call for federal involvement -- ahead of Michigan's Tuesday primary.

Lines for the caucuses in Portland stretched at least a quarter mile, and the Maine Democratic Party was forced to make changes to the voting process. It allowed people to essentially cast an absentee ballot inside the caucus site instead of physically staying for a caucus count.