Hillary Clinton's path to victory in Iowa is cluttered by the dueling problems of her email scandal and the excitement building behind her chief rival, both of which may threaten the outcome of a contest Clinton was once heavily favored to win.

Sen. Bernie Sanders' recent rise in Hawkeye State polls has coincided with a dip in support for Clinton, which occurred during several weeks of renewed attention to her private email use.

But Democrats seem to disagree on whether Clinton's slippage is due to her rival's growing popularity or her own inability to retire questions about her handling of potentially classified information while serving as secretary of state.

"It's pretty clearly Bernie Sanders' aspirational message and sort of the passion that he's tapped into," former Indiana Sen. Evan Bayh told the Washington Examiner of why he thinks Clinton's lead in Iowa has shrunk.

"This is sort of the phase in the campaign, maybe on both sides, where voters are angry about Washington, they're upset about the direction of the country, and they want to send a message to the establishment of both parties that they want change," said Bayh, who also served as a two-term Democratic governor of Indiana.

However, after the Iowa and New Hampshire contests, "that may be somewhat cathartic," he said.

"The voters will then focus on the reality that they are electing a president, they're not just sending a message," Bayh added.

Brad Bannon, a Washington, D.C.-based Democratic strategist, said he thinks Clinton's own record is more of an obstacle to her success than the Vermont senator.

"It's more a matter of Hillary than Bernie," Bannon said.

"I think what Bernie is mostly doing is getting disaffected Clinton voters. So I think when she hits a pothole, that's when her vote goes down, and Bernie inherits it afterward."

Clinton's support in Iowa now sits at 46 percent, just a notch above Sanders' 45.4 percent, according to the RealClearPolitics average of polls.

The narrowing margin has thrown the outcome of the upcoming caucus into contention, with observers calling the race a true toss-up five days ahead of the vote.

Ford O'Connell, a Republican strategist, said a Hawkeye State loss could exacerbate Clinton's already mounting email problems.

"I'm thinking that if I'm her, I'm rubbing a rabbit's foot to win Iowa," O'Connell said. "If this Sanders enthusiasm gap is as big as some people believe, then he's likely to win Iowa, because it's a caucus."

Sanders' exploding popularity is Clinton's biggest problem "in the short run," he noted, because it could cost her a win right out of the 2016 gate. That could, in turn, allow the email controversy to drag her down further.

"Anything that makes her look vulnerable is not good, because then it contributes to opening the wound greater on the email scandal," O'Connell said.

Clinton could face a parade of uncomfortable questions in the weeks between a potential Iowa defeat and an all but certain New Hampshire loss and the start of her comeback in South Carolina, where she enjoys what some have dubbed a "firewall" of minority support.

"If you're looking at the national primary polls, Bernie has very little support among black and Latino Democrats," Bannon said. "It matters a lot in South Carolina and Nevada and Texas and the other states that are having primaries after New Hampshire, up to Super Tuesday."

Bayh said Sanders' high numbers in the first two primary states could partly be attributed to the fact that Iowa and New Hampshire have some of the "most liberal" electorates.

"The other thing he's got going for him is, he's got a very extensive fundraising base of people giving lots of small donations," Bayh said. "And so historically, candidates stop running for president when they run out of money. It doesn't look like Sen. Sanders will have to do that for quite a long time. There'll be nothing that will force him to get out of the race."

At a televised New Hampshire townhall Monday, Clinton declined to admit error in her decision to set up a private server in her basement despite an FBI investigation into the arrangement. Her response marked a departure from the contrite tone she struck last summer, when she apologized to voters for refusing to use her government-issued email account.

Democratic primary voters seem increasingly unphased by the specifics of the email controversy, although the slow-brewing controversy is already emerging as a popular weapon of her potential Republican opponents that will surely become a feature of the eventual nominee's general election campaign against her.

"Basically, her biggest problem is people, question her trustworthiness and her honesty," Bannon said. "And the flip side of this is, Democratic primary voters like her because she is strong, tough and they think she is a good leader. That's the yin and yang of Hillary Clinton."