Pete Buttigieg vaulted into the lead in the Democratic Party's 2020 presidential nominations race in early-voting Iowa, according to a poll Tuesday, as billionaire and fellow moderate Michael Bloomberg stepped closer to a White House run.
Both moves come at the expense of former vice president Joe Biden, whose centrist campaign has struggled to maintain its frontrunner status.
And they signal an unsettled field with voters far from coalescing around a single candidate less than three months before the first votes in Iowa.
The Monmouth University poll marks the first time that Buttigieg, mayor of South Bend, Indiana and at 37 the youngest candidate in the race, has topped a statewide presidential survey, firming his stature in the crowded battle to challenge President Donald Trump.
Buttigieg leads with 22 percent support while Biden secured 19 percent, according to the poll of likely voters in Iowa, which votes first in the nomination process.
The race's two leading progressives, senators Elizabeth Warren and Bernie Sanders, came in at 18 percent and 13 percent respectively.
The poll surveyed 451 Iowans likely to attend the state's caucuses next February, and the margin of error is plus or minus 4.6 percentage points.
In national polling Biden is the frontrunner, and Buttigieg remains in fourth, behind Warren and Sanders.
But the Iowa poll confirms a rising trend for Buttigieg. His support surged 14 points since the last Monmouth poll in August, while Biden's slid seven points.
Buttigieg "is doing well with voters regardless of education or ideology," said Patrick Murray, director of the independent Monmouth University Polling Institute.
The poll also shows that many Iowans are not fully committed, with 53 percent of likely caucusgoers acknowledging a high or moderate possibility they will change their minds.
In a further unexpected twist to the Democratic race, defeated 2016 candidate Hillary Clinton on Tuesday appeared to not rule out joining the fray.
She told BBC radio "many, many people" were pressuring her to run but "as of this moment... that is absolutely not in my plans."
The lack of a firm frontrunner could encourage Bloomberg, the former New York mayor.
"Officially filed in Arkansas to be on the ballot for the Democratic primary," tweeted Bloomberg with a photograph of himself submitting the paperwork -- four days after doing the same in Alabama.
"We must defeat Trump. He has failed us at every turn," the 77-year-old added.
Both states have early deadlines to register for the primaries.
- Reversing course? -
Bloomberg's personal appearance to sign his ballot papers in Little Rock was a strong hint that the centrist tycoon will officially leap into the already-crowded Democratic field.
"If he runs, he's going to go to states that Democrats never go to in the primary campaign," Bloomberg spokesman Jason Schechter told The New York Times. "We're starting that today in Arkansas."
Bloomberg had said back in March that he would not run.
He has changed his political affiliation on multiple occasions, including switching from Democrat to Republican when he successfully ran for mayor of New York in 2001. He became an independent six years later.
Bloomberg is said to be concerned that a progressive Democratic nominee like Sanders or Warren would aid Trump's re-election.
By filing in Arkansas and Alabama -- which vote on Super Tuesday, March 3, along with 12 other states -- Bloomberg is signalling he might forego campaigning in the four states that vote earlier in February: Iowa, New Hampshire, Nevada and South Carolina.
No candidate in modern US politics has eschewed campaigning in early voting states and won their party's nomination.
Bloomberg founded a media company that became a multi-billion-dollar behemoth, and ran the nation's largest city, with 8.6 million residents, for 12 years.
But Bloomberg, like Trump, is a white male septuagenarian New York billionaire.
Buttigieg is about half their age, from the midwest, and the first major openly gay presidential candidate.
"I'm as opposite from this president as it gets," he told AFP recently in New Hampshire.