With just more than two weeks before Iowa holds the first nominating contests of 2016, former President
Even her supporters say they can't predict a win, and fear the fallout of a loss.
"It could go either way. It's a jump ball," said veteran Democratic strategist Brad Armstrong, who endorsed Clinton last summer. If Clinton loses, "it's no secret it would be a problem. Of course, not one that is insurmountable, but it would certainly prolong the primary in a way I don't think the Clinton campaign would want."
Bill Clinton remains a masterful campaigner, and the crowds over the course of two days punctuated his remarks with laughter, whoops of agreement and warm, sustained applause, exactly the kind of enthusiasm his wife's campaign needs to keep pace with the zeal Sanders is generating to help ensure that supporters turn out to caucus for her.
Bill Clinton never mentioned Sanders or the tightening of the race in his raspy, low-key remarks.
"I don't know if I'm any good in this election because I'm a happy grandfather, I'm not really mad anymore," he joked in front of a crowd of nearly 300 at a community college in Marshalltown on Friday.
The crowds particularly warmed to Clinton when he spoke about his relationship with his wife. In Marshalltown, he recalled meeting his wife 45 years ago while they were law students.
"There was this energy coming off her, and I walked up behind her and I almost touched her on the back and I lost my guts. I thought, this is not going to be some drive-by," he said.
Hillary, he said, saw him staring at her in the library, walked up and said, "If you're going to keep looking at me and I'm going to keep looking back, we at least ought to be introduced. I'm Hillary Rodham, what's your name?"
Bill continued, telling the crowd: "I couldn't remember my name. And in one way or another we've been together ever since."
He recounted his wife's accomplishments since then -- work she did to help children and the poor in Arkansas, bipartisan efforts while in the U.S. Senate and foreign policy achievements as secretary of State.
The former president argued that the nation’s lot has improved during
"Decide what's best for America," Clinton said. "It is not close who would be the best commander-in-chief. It's not close who's the best change agent when it comes to economic and social growth. It is not close who has demonstrated the toughness to preserve our Constitution, to preserve our basic liberties, and the self-confidence to cooperate with people across party lines and geographic lines when necessary. That's what you need."
Pam Spears and LeeAnn Toms, friends from nearby Toledo, did not need to be convinced.
"I've been a Hillary fan forever and a day," said Spears, who caucused for her in 2008. "She's a tremendous human being with a lot of talent and expertise, and as far as I'm concerned, that's what the country needs."
Toms caucused for Obama eight years ago, drawn by his charisma. But this time, she said she is set on Clinton because of her decades of service to the nation. But the retiree and other Clinton supporters, such as Tim Wicks of Des Moines, have nothing negative to say about Sanders, but are worried about his candidacy.
"He's got quite a following and he's getting people excited. It's going to be a battle," said Wicks, 61, who plans to caucus for Clinton.
Indeed, some in the Bill Clinton-adoring crowd remained undecided, saying they admired both candidates.
Jane Holder, 65, said she was drawn to see the former president, but remains undecided about whether she will caucus for Clinton or Sanders.
"They both believe in the things I want to happen to our country, so I think they're both strong candidates," said Holder, a Marshalltown resident. "I think they would both be very good."
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