Joe Biden and Elizabeth Warren lead the pack in polling before fourth Democratic debate in Ohio

WASHINGTON – As 12 of the remaining 19 Democratic presidential candidates head into Westerville, Ohio, on Tuesday for the fourth primary debate, former Vice President Joe Biden and Sen. Elizabeth Warren of Massachusetts are at the front of the pack, according to polls.

Who's leading between Biden and Warren? It depends on which polling outfit you ask. Biden leads Warren 32%-21% in the latest update from Politico-Morning Consult and 32%-22% in a poll released last week by Fox News. Warren leads by 3 percentage points in a Quinnipiac University poll published Monday and by 4 points in an Economist-YouGov poll published last week.

Until recently, Biden had led in virtually every major poll published since the end of 2018, but Warren has come out on top in eight of the past 15 national polls.

Monday's poll is the third survey in a row from Quinnipiac in which Warren finished ahead of Biden.

"For Sen. Warren, the third straight time essentially tied at the top is the charm," Quinnipiac polling analyst Tim Malloy said. "Her candidacy clearly has staying power going into the debate."

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Voters have the highest expectations for Warren heading into Tuesday's debate: 29% of Democrats and those who lean Democrat say they think she will perform the best, 25% say Biden and 13% say Bernie Sanders, according to a Politico-Morning Consult poll conducted from Oct. 11-13.

Fifty-eight percent of those voters say they are motivated to watch the debate, and 27% say they are not motivated. Among all registered voters, 49% say they are motivated to watch, and 46% say they aren't.

Fifty-eight percent of registered voters say the debate is at least "somewhat important," and 33% say it is "not very important" or "not important at all." Among Democrats and Democrat-leaning voters, 71% say it is important, and 12% say it is not.

Last month, Warren began to pull ahead of Vermont Sen. Sanders, who has come up third in most recent polls.

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Since July, Warren and Sanders had been locked in a virtual tie for second place in a majority of polls. The two have been the favorites of liberal voters in contrast with Biden who is the choice of more moderate Democrats. As Warren surged to compete with Biden for the top spot, Sanders – who suffered a heart attack this month – faded, finishing third in all but four of 22 polls conducted since mid-September.

Warren is the choice of 50% of Democratic voters and independents who lean Democratic who identify as "very liberal" in the poll from Quinnipiac. Sanders and Biden are tied at 14% within that group. Among those who call themselves "somewhat liberal," Warren finishes first at 34%, Sanders comes in at 17% and Biden at 15%.

Biden is the clear favorite among those who identify as conservative Democrats at 36%; Warren comes in second at 19%, and Sanders is third at 6%.

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Warren – whose declaration "I have a plan for that" has become synonymous with her campaign – holds a decisive lead as the candidate with the best policy ideas at 40%, ahead of Biden at 16% and Sanders at 12%, according to Quinnipiac.

But Democratic voters indicate defeating President Donald Trump in the general election is their top priority, and about half of Democratic voters see Biden as the candidate best equipped to pull that off. Forty-eight percent say Biden has the best chance of defeating Trump, and 21% see Warren as the candidate with the best shot. While Biden has hovered at 42% to 56% in Quinnipiac polls on this question, Warren had never finished higher than 9% in previous surveys from the pollster.

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When asked which Democratic candidate they think would be the best leader, 32% say Biden and 28% say Warren.

On the question of impeachment, 46% say Trump should be removed from office, and 48% oppose such a move. A narrow majority of 51% approve of the Democrat-controlled House's move to open an impeachment inquiry, and 59% say they disapprove of the way Trump has responded to the inquiry. Fifty-one percent say the impeachment is a "legitimate" investigation, and 43% say it is a "political witch hunt."

Though 66% say it is "not acceptable" for a president to ask a foreign leader to investigate a political rival, as Trump encouraged Ukraine to look at Biden, only 44% say that is a good enough reason to remove a president from office.

The Quinnipiac poll was conducted Oct. 11-13 among 1,195 registered voters. It has a margin of error of plus or minus 3.5%.

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This article originally appeared on USA TODAY: Elizabeth Warren and Joe Biden lead in polls ahead of Democrat debate