WASHINGTON (AP) -- There was a time when Democrats fretted about Hillary Clinton's presidential campaign becoming a coronation and leaving her without the tests of a primary season to prepare for a general election matchup against the Republican nominee.
No one is worried about that anymore.
In the past two weeks, the Democratic race has gone from a relatively civil disagreement over policy to a contentious winter competition between former Secretary of State Clinton and Vermont Sen. Bernie Sanders.
Clinton's institutional strength and her support among the minority voters who make up a large portion of the party's base still put her in a formidable position, even as polls show Sanders surging in Iowa and maintaining an edge in New Hampshire.
But should Sanders prevail in those first two states on the 2016 campaign calendar, Clinton's bid to succeed President Barack Obama may mean a much longer and messier path than her supporters once envisioned. It would plunge Democrats into the kind of primary fight they have gleefully watched Republicans struggle to contain in the past year.
"You have to look at these numbers and say there's a real race going on," said Democratic pollster Mark Mellman. "It's a race where Hillary Clinton has significant advantages in the long run. But it's a real race."
The contest was certain to intensify this weekend, with the Democratic candidates gathering in Charleston, South Carolina, on Saturday night for a party dinner and the annual fish fry hosted by Rep. James Clyburn, D-S.C. Then there's the Sunday night debate, the final one before the Iowa caucuses on Feb. 1. The New Hampshire primary is Feb. 9.
"I think it is a new phase of the campaign," said Joel Benenson, Clinton's chief campaign strategist. "We talked about how close this was going to be in (Iowa and New Hampshire). They always are historically and we're ready to have this debate engaged."
In the past week, Clinton has shifted course in apparent response to Sanders' strong poll results. She has stepped up her criticism of her rival, a self-described democratic socialist, after carefully avoiding that during the campaign.
The new approach carries risks. Sanders is popular with liberals who are part of the coalition that Clinton will need to win the White House.
Clinton and her supporters still remember her disappointing third-place finish in Iowa in 2008 against Obama. Clinton's team has retooled her schedule to add stops in Iowa in the week ahead. The candidate has made near-daily television appearances where she has challenged Sanders' stances on health care and gun control.
Clinton and Sanders were each booked on four Sunday morning news shows.
Her campaign is sending out top party representatives, starting with former President Bill Clinton, to make her case in early voting states. Daughter Chelsea Clinton has offered critical words about Sanders, leading to a back-and-forth over his health care plan.
"They're very afraid of a repeat in 2008 and they're getting very aggressive," said Sanders campaign manager Jeff Weaver. "I expect at any moment now they'll go hard negative on us and we're prepared for that. But we won't be negative on them."
Clinton has tried to dismiss Sanders' proposals as unrealistic and disingenuous. She points to his 2005 vote for legislation giving gun manufactures immunity from lawsuits as a sign that the senator wouldn't fight forcefully enough against powerful interest groups.
Sunday's debate is in the city where a 21-year-old white man shot and killed nine people attending a prayer service at an African-American church last summer. The setting may give Clinton a chance to confront Sanders on his past votes related to gun control.
But in a campaign that has seen billionaire Donald Trump rise to the top of the Republican presidential field by capitalizing on an electorate angry with the political establishment, Clinton may once again be embracing the mantle of experience at a time when outsider status is in vogue.
"What she's trying to do is cast Bernie as, I don't want to say a protest candidate, but as a message candidate against someone who is grounded in the reality of governance," said former Obama campaign strategist David Axelrod. "The danger is that you also make yourself an exponent of governance the way people see it today.
"In an anti-establishment time," Axelrod said, "you're essentially branding yourself as the establishment candidate."
The campaign could take a much tougher turn in the weeks ahead.
Clinton's campaign complained this past week when Sanders aired an ad that suggested Clinton wouldn't be tough enough on Wall Street. That could clear the way for Clinton's team to retaliate with its own critical advertising.
After Iowa and New Hampshire, the calendar seemingly swings in Clinton's favor. She has an edge in Nevada, the first caucus state with a significant segment of Latino voters, and in South Carolina, where black voters make up more than half of the electorate.
From there, the campaign will play out in a series of Southern states holding contests on the March 1 "Super Tuesday" primaries, where African-American voters are pivotal.
The question for Sanders is whether he can expand his support beyond the white voters who dominate the first two contests in Iowa and New Hampshire.
"If — and it's a very big if — Bernie Sanders wins both Iowa and New Hampshire, there will be a lot of heartburn. There will be a lot of handwringing," Mellman said. "But for him to win the nomination over the long term, he's got to get beyond that base."