Minnesota U.S. Sen. Amy Klobuchar remains stalled behind a clutch of top Democratic contenders for president in Iowa, gaining little traction in an influential Des Moines Register/CNN/Mediacom Iowa Poll released Friday.

Three weeks ahead of the first-in-the-nation caucuses, Vermont U.S. Sen. Bernie Sanders pulled ahead of the field with 20% of likely Democratic caucusgoers naming him as their first choice for president. Massachusetts U.S. Sen. Elizabeth Warren polled 17%, former South Bend, Ind., Mayor Pete Buttigieg garnered 16%, and former Vice President Joe Biden got 15% — putting them in a virtual statistical tie in the race for the Democratic nomination.

Klobuchar trails with 6% support, marking no change from the same poll two months ago despite what her campaign considered a wave of momentum in recent weeks.

The poll, released on CNN and DesMoinesRegister.com, asked likely Democratic caucusgoers their top choice for president among 14 candidates for their party's nomination. The poll serves as an early barometer of where the 2020 presidential candidates stand at a crucial juncture in the primary contest.

"The campaign continues to see growing momentum since the senator's debates," a Klobuchar campaign spokesperson said Friday night. "Senator Klobuchar has more endorsements of legislators and former legislators in the state of Iowa than any other candidate. This is one poll. Several others have seen even bigger numbers."

"We are looking forward to the debate in Iowa on Tuesday where the senator is one of only six candidates on the stage."

That's in reference to the results coming ahead of Friday's midnight deadline for candidates to meet the Democratic National Committee's polling requirement to participate in Tuesday's debate in Des Moines, the last before Iowans caucus on Feb. 3.

Besides Klobuchar, five others have qualified for what also will be the first debate of 2020: Biden, Buttigieg, Sanders, Warren and businessman Tom Steyer.

That debate may be a "make-or-break" moment for Klobuchar, said Steven Schier, retired Carleton College political professor. She'll have to be aggressive and go after some of the candidates just as she did with Buttigieg in the last debate, he said.

"She has to develop momentum coming out of it," Schier said. "The traditional wisdom is that there are three tickets out of Iowa. The top three … have a future in the nomination contest."

Some Iowa political leaders, however, widely believe that there are five tickets out of Iowa this year.

Cracking that top tier is especially important for Klobuchar because it would help her raise more money and get more media attention, which would translate into more momentum, Schier said. It will be a tough task, because the contenders ahead of her are formidable, but it's not impossible. There seems to be a bit of flux among the leaders, he said.

"That's good news for Amy, because nobody in the top four has broken into a clear lead and left the pack behind," he said.

She's "positioned very well," said Larry Jacobs, political science professor at the University of Minnesota's Humphrey School of Public Affairs. "If you told me a year ago that Amy Klobuchar was going to be right in the mix a few weeks before the Iowa caucus, I wouldn't have believed it."

The latest poll, along with an influx of donations in the last quarter, are good signs, he said. "It tells me there are a good number of Democratic voters and donors who aren't that comfortable with the top group."

The poll of 701 likely Democratic caucusgoers was conducted Jan. 2-8 and has a margin of error of plus or minus 3.7 percentage points.

In the last Des Moines Register poll in November, Buttigieg rocketed ahead of Warren, the previous leader in the poll, as well as Biden and Sanders, who were tied for third at the time. Klobuchar also finished fifth in that poll with 6% support.

"[Voters] are moving around among the top four candidates," Schier said. "If she can get a superior debate performance, perhaps she can get some of those wavering voters to move in her direction on caucus night."

Klobuchar, who recently completed a campaign milestone with stops in all 99 Iowa counties, has been riding a new wave of national attention after well-received debate performances in November and December. Her campaign reported that she collected $11.4 million in contributions in the last three months of 2019, nearly half of the more than $25 million she has raised since joining the presidential contest last Feb. 10.

Klobuchar is counting on Iowa to propel her into the top echelon of the Democratic primaries heading into the early voting states of New Hampshire, Nevada and South Carolina.

Doubling down on Iowa, where she has put much of her effort, Klobuchar has released a new ad to kick off her "Day of Action" in the Hawkeye State — an organizing push on Saturday that will include canvassing and phone bank events to pump up support before the caucuses.

The New York Times contributed to this report.