Sen. Elizabeth Warren is facing the highest expectations of any of the candidates on tonight's debate stage, according to a new POLITICO/Morning Consult poll.

Nearly a third of Democratic primary voters — 31 percent — expect Warren to perform the best during Tuesday's debate. That's up 12 points from the polling ahead of the September debate, when 19 percent of Democratic primary voters said they believed she would perform the best.

Twenty-five percent said they believed former Vice President Joe Biden would perform the best, followed by 12 percent for Sen. Bernie Sanders.

There's also early signs that Democratic primary voters are growing tired of the debates. Tonight's debate is the fourth of 12 planned debates.

Enthusiasm for the debate is still incredibly high among Democratic primary voters: 72 percent said they are motivated to watch tonight's debate. But that's a drop from 79 percent of Democratic primary voters who said they were motivated to watch September's debate.

Voters also increasingly agree that the large debate stages are a bad idea. Twelve candidates will meet for Tuesday's debate, two more than the September debate. The debate will be the largest televised presidential primary debate ever, regardless of party.

Sixty-three percent of Democratic primary voters think there are too many candidates on the debate stage.

Candidates on the fringe of the debate stage have repeatedly complained about the process, arguing that the Democratic National Committee was unnaturally winnowing the field by increasing the threshold to participate in the debates. However, a slim majority of primary voters said in a previous POLITICO/Morning Consult poll that 10 candidates on the stage was too many, and more voters now believe that to be true with 12 candidates on tonight's stage.

The next debate in November will likely feature less than 12 candidates after the DNC raised the thresholds to participate. However, the slightly higher requirements to get on stage are not expected to dramatically decrease the size of the stage. Eight candidates have already qualified, and the qualification deadline closes on Nov. 13.

However, voters do still believe that the debates are incredibly important in the process, with 85 percent of voters saying the debates were either "very" or "somewhat" important.

The POLITICO/Morning Consult poll was conducted Oct. 11-13 online among a national sample of 1,993 registered voters, including 860 voters who said they're likely to vote in the Democratic primary. The full survey of registered voters has a margin of sampling error of plus or minus 2 percentage points.