Democratic voters can’t decide on a front-runner to take on President Trump in November.

New polling shows a sharply divided field, with socialist Bernie Sanders leading on one side and a slate of more centrist Democrats jockeying for front-runner status on the other.

The split among non-Sanders voters has led to a level of uncertainty that hasn’t existed in a Democratic primary for decades, said pollsters.

“I don’t think we’ve seen a contest where, at this point, it hasn’t really emerged who the top two or three candidates were going to be,” Patrick Murray, director of the Monmouth University Polling Institute, told the Washington Examiner. “Maybe in the 1990s or the 1988 Democratic presidential primary.”

Monmouth released a poll on Tuesday showing Democrats in the key swing state of Virginia remain uncertain about who they want to become the nominee.

Only 1 in 4 voters “are firmly set” on a presidential candidate, and a majority of voters are open to switching support to another candidate by Super Tuesday on March 3, when 14 states and entities hold primaries and caucuses.

Sanders, 78, is leading the entire pack nationally, but, just recently, former Vice President Joe Biden was ahead of the candidates in most of the polls.

There could be more dramatic changes, Murray said.

“Usually, by now, you have an idea that this person is the front-runner and [that] there is still a chance for one or two others to catch up,” he said. “We are not in that position right now. It could change tomorrow and be entirely different.”

Biden’s poll numbers plummeted after he placed poorly in both the Iowa caucuses and the New Hampshire primary, but some predict he will revive his campaign in Nevada and South Carolina, where polling has him placing in second and first place, respectively, according to the latest RealClearPolitics polling averages.

A poll issued by the liberal Data for Progress showed Sanders with a 19-point lead over Biden, 77, but a poll conducted by WPA Intelligence on behalf of the Las Vegas Review-Journal and AARP Nevada found Biden trailing Sanders by 7 points.

A Telemundo poll of Latino voters showed Biden leading Sanders, 34% to 31%.

In Virginia, Sanders and Biden are jockeying for the lead along with former New York City Mayor Michael Bloomberg, whose massive and unprecedented spending on campaign advertising has pushed him into striking distance of the lead.

A YouGov/ Yahoo! News survey of registered U.S. voters found 68% had seen a Bloomberg television ad.

The Monmouth poll found Bloomberg and Sanders tied for Virginia’s lead with 22% of the vote, closely trailed by Biden, who was backed by 18%.

Most of the remaining group of Democratic voters are split among former South Bend, Indiana, Mayor Pete Buttigieg (11%), Minnesota Sen. Amy Klobuchar (9%), and Massachusetts Sen. Elizabeth Warren (5%).

Like voters in other states, Virginia Democrats said the most important attribute they seek in a candidate is the ability to beat Trump in November. The Monmouth poll found that 84% of voters believe beating Trump is either the most important factor in choosing a candidate or as important as a top policy concern.

Bloomberg’s entry into the race beginning on Super Tuesday could further shake up the race, particularly if he outperforms Biden and begins drawing away Biden supporters.

An NPR/PBS NewsHour/Marist poll found Sanders on top, with 31% of the vote. Bloomberg ranked second, with 19%, which qualifies him for Wednesday's Democratic debate in Las Vegas.

Bloomberg’s participation will provide voters the first chance to see the billionaire perform outside his scripted campaign ads, which have largely been responsible for propelling him toward the lead.

The same NPR poll showed Bloomberg with just 4% of Democratic support in December.

Bloomberg does not appear on the ballot in any of the first four contests and has never joined the other candidates on the debate stage.

The poll shows Bloomberg beating Biden among centrist voters with 29% to 23%, indicating they may be starting to look at Bloomberg as a more viable alternative to Biden.

“Bloomberg is probably going to have an uncomfortable night," University of Virginia political science professor Larry Sabato told the Washington Examiner. “He’ll be attacked by the other five candidates, probably repeatedly. His TV ads allow him to present only the positive image he prefers, but Democratic viewers are going to be learning things that won’t please them.”

Sabato said he expects Bloomberg to fight back.

“He probably should. Biden liked to step back and take the heat while showing he was the adult in the room,” Sabato said, "and we see where that has gotten him.”