Biden and Vermont Sen. Bernie Sanders are in the top tier in a Monmouth University poll with 26% and 21%, respectively. Massachusetts Sen. Elizabeth Warren is in third place with 17%

Another poll out Tuesday from Quinnipiac University finds Biden in the lead with 29%, followed by Bernie Sanders at 17%, and Elizabeth Warren at 15%. No other candidate was in double digits.

Warren's support in the Monmouth poll has dropped in each of their past three polls, from 28% in September to 23% in November and 18% now. She also saw a downtick in CNN's poll with SSRS that was released in late November, as well, from 19% in October to 14%.

In Quinnipiac's poll, Warren was steady, while both Sanders and Biden saw very slight upticks. Buttigieg has dropped 7 percentage points since Quinnipiac's November poll, which was among Buttigieg's best of the cycle.

Making up the rest of the field in Monmouth's poll is South Bend, Indiana, Mayor Pete Buttigieg with 8%, former New York City Mayor Michael Bloomberg with 5%, Minnesota Sen. Amy Klobuchar with 4%, businessman Andrew Yang with 3%, and New Jersey Sen. Cory Booker with 2%. No other candidate received above 1% in the new poll.

The Quinnipiac poll is the fourth qualifying poll for Yang at 4%, putting him on the debate stage in December.

Bloomberg received his first and second polls that could qualify him for the December Democratic primary debate, but with the deadline on Thursday, he would need two more polls and to hit the fundraising threshold in order to make the stage. No other candidate qualified for the debate stage with this poll.

So far, Biden, Sanders, Warren, Buttigieg, Klobuchar, businessman Tom Steyer, and Yang have qualified. Hawaii Rep. Tulsi Gabbard has hit the fundraising threshold and only needs one more poll to qualify for the December debate before Thursday but she has stated that even if she qualifies, she doesn't plan on attending.

Warren still tops the favorability ratings in Monmouth's poll among registered Democrats and Democratic-leaning independents, with 76% favorable, 15% unfavorable (+61), though down slightly since November (+70). She's followed by Biden (+56) and Sanders (+53).

Bloomberg starts the race with tepid feelings among all Americans following last month's kickoff of his campaign. Despite polling at 5% in both Monmouth and Quinnipiac (after not being asked in most polls last month), around a quarter of Americans have a favorable opinion of him, 54% unfavorable, with 40% favorable and 39% unfavorable among Democratic voters, according to the Monmouth poll. The Quinnipiac poll tells a slightly similar story; 33% Democratic voters have a favorable opinion, 24% unfavorable.

Almost two-in-five registered voters say their mind is made up, according to Quinnipiac, while 59% say they may still change their minds. Biden and Sanders voters are the most likely to say they've made their choice (46% and 48%, respectively).

Democratic voters would still prefer a candidate who could beat President Donald Trump (56%) over someone with whom they completely agree on the issues but would have a harder time winning (30%), which has remained steady since earlier this year.

Slightly over two-in-five Americans want Trump reelected, the highest it has been in Monmouth's polling since they started asking in November 2018, but a majority would still prefer someone else as president (54%).

In a series of head-to-head matchups in the Quinnipiac poll, six of the potential Democratic nominees each lead Trump by a significant margin in each one (Biden by 9 percentage points, Sanders +8, Warren +7, Bloomberg +6, Buttigieg +5, and Klobuchar +4).

Trump's approval in Quinnipiac remains steady -- 41% approve, 55% disapprove. A very slim majority still say not to impeach Trump should not be impeached and removed from office (51%), while 45% say he should be, steady since late November.

The Monmouth University poll was conducted December 4-8 among a random national sample of 838 registered voters, including 384 Democrats and Democratic-leaning independents who are registered to vote. Results for all registered voters have an error margin of plus or minus 3.4 points, it is plus or minus 5 points for potential Democratic voters.