LONDONBERRY, N.H. -- Democratic presidential candidates Hillary Clinton struggled to defend herself against Bernie Sanders' insinuations that she's beholden to Wall Street, while Sanders faced fresh doubts about his experience on foreign policy, a day after jousting in a feisty debate.

Meanwhile, Marco Rubio shouldered intensifying attacks Friday from a herd of moderate-leaning Republicans who fear a strong Rubio showing in Tuesday's New Hampshire primary could spell the end for their frazzled presidential campaigns.

As candidates crisscrossed the state, the all-out push for votes despite a snow storm that forced Sanders and Republican candidate Donald Trump, to cancel afternoon events, illustrated the growing stakes.

For Clinton, who revived her campaign here in 2008 after a bruising Iowa loss, the final sprint in New Hampshire offered an unpleasant reckoning with reality: Once again, the former first lady is locked in a bona fide contest for a nomination most Democrats had thought was hers for the taking.

A Boston Globe/Suffolk University poll released Friday showed Sanders with an expanded lead over Clinton in New Hampshire, though the two are running neck-and-neck nationally.

Sanders and Clinton tussled aggressively in their first one-on-one debate Thursday, their last before the primary, with Clinton accusing the Vermont independent of an "artful smear" for suggesting her speaking fees and donations from Wall Street firms bound her to corporate interests. Sanders countered that Clinton "does represent the establishment."

Clinton's campaign tried to flip the script on Sanders by arguing she's the opposite of an establishment contender.

But Sanders was sticking to core messages in the final days before the primary: government-run health care, free tuition at public universities and an end to gigantic, all-powerful financial institutions.

"I want to see banking become boring again," Sanders said. "Remember boring banking?"

On the Republican side, polls showed Rubio on the ascent both in New Hampshire and nationally, raising his hopes that Republican Party leaders would soon unite behind him in a bid to sideline their two polarizing front-runners: Trump and Texas Sen. Ted Cruz.

Jeb Bush accused Rubio of a lacklustre set of accomplishments. Bush, campaigning with his mother, former first lady Barbara Bush, summed up the Florida senator's achievements in one word: "Nothing."

Cruz, the victor of last week's lead-off Iowa caucuses, was struggling to put complaints about his campaign's tactics in the rear view mirror, as new evidence emerged of what challenger Ben Carson has dubbed "dirty tricks."

Fueling the dust-up were rumours spread by Cruz'Clinton struggles to defend Wall St. linkss campaign hours before the Iowa caucuses about Carson dropping out of the race. Trump has also cried foul, arguing Cruz "stole" the election by peeling off Carson supporters to surge past Trump.

Before New Hampshire votes, the Republicans planned one last debate showdown on Saturday.

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Associated Press writers Jill Colvin in Londonberry, New Hampshire, Josh Lederman in Washington contributed to this report.