Vermont Sen. Bernie Sanders has ridden a big turnout to victory over former Secretary of State Hillary Clinton in Maine's Democratic presidential caucuses. 

Sanders beat Clinton by a margin of nearly 2 to 1. He told supporters in Portland this past week that he'd win if there was a strong turnout.

And the turnout was so big Sunday that some voters had to wait in line for more than four hours in Portland.

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The vote came a day after Texas Sen. Ted Cruz won the GOP caucuses.Unlike Saturday's GOP caucuses, the results aren't binding.

The votes will be used to select a slate of delegates to the state convention, where national delegates will be elected. Maine will send 25 delegates and 30 superdelegates to the national convention in Philadelphia.

The lines were so long at some of Maine's Democratic presidential caucuses that the Senate Democratic leader is calling for reinstating primaries.

Sen. Justin Alfond of Portland says it's time to talk about a more efficient way of conducting Maine's presidential preference votes. He pointed to lines of more than three hours Sunday, along with similar caucus delays in 2008.

He says he's going to introduce a bill Monday that would require a return to the primary system for both parties. In primaries, parties cast tallies as they would on Election Day, and the election is conducted by state and municipal officials.

Caucuses are run by the parties and require a greater time commitment because the local gatherings involve discussion and speeches on behalf of candidates.

Participants today were given the option of voting via absentee ballot.

Jeremy Kennedy, the party's executive director, said the option was opened up to those in line who wanted to vote but didn't want to wait to participate in the caucus.

Hundreds were stuck in a line outside Deering High School that snaked a half-mile from the entrance. Waiting Democrats started the wave, and some people ordered pizza. There were pets, babies and strollers, and most people seemed to be in good spirits.

Kennedy said the party had counted on participation similar to the 2008 caucuses. But he said a flood of new registrants underscored the higher-than-expected numbers.

No one who wanted to participate in caucuses was turned away.

On Sunday night, Clinton and Bernie Sanders appeared in a prime-time debate in Flint, Michigan. The Michigan primary is Tuesday.