The Democratic race is unusually large heading into Monday’s Iowa caucuses, with four presidential candidates locked in a fight for victory in Iowa and others still in a position to pull off surprisingly strong finishes.

Many campaigns were looking to final weekend polls to provide some measure of clarity.

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Polls show former Vice President Joe Biden in a tight race in Iowa with Sens. Bernie Sanders of Vermont and Elizabeth Warren of Massachusetts, as well as Pete Buttigieg, former mayor of South Bend, Ind.

Minnesota Sen. Amy Klobuchar and entrepreneur Andrew Yang also are competing aggressively in the state.

An Emerson College poll released Sunday night found Sanders leading with 28 percent support, Biden at 21 percent, Buttigieg at 15 percent, Warren at 14 percent and Klobuchar at 11 percent.

A CBS News poll had Biden and Sanders holding the lead with 25 percent each, Buttigieg with 21 percent, Warren at 16 percent and Klobuchar at 5 percent.

Late Saturday, a final CNN and Des Moines Register poll opted not to release their survey because of concerns that the results may have been compromised.

For the first time, the Iowa Democratic Party will release three sets of results: who voters align with at the start of the night, who they pick after voters supporting nonviable candidates get to make a second choice, and the number of state delegate equivalents each candidate gets.

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The new rules were mandated by the Democratic National Committee (DNC) as part of a package of changes sought by Sanders following his loss to Hillary Clinton in the 2016 presidential primaries. The revisions were designed to make the caucus system more transparent and to make sure that even the lowest-performing candidates get credit for all the votes they receive. But party officials in Iowa and at the DNC have privately expressed concerns that multiple campaigns will spin the results in their favor, potentially creating chaos on caucus night.

The Associated Press contributed to this report.