Poll shows Sanders gaining on Clinton

Vermont Sen. Bernie SandersBernard (Bernie) SandersSchumer: Franken should resign Franken resignation could upend Minnesota races Avalanche of Democratic senators say Franken should resign MORE (I) is chipping away at Hillary ClintonHillary Diane Rodham ClintonGrassley blasts Democrats over unwillingness to probe Clinton GOP lawmakers cite new allegations of political bias in FBI Top intel Dem: Trump Jr. refused to answer questions about Trump Tower discussions with father MORE’s lead nationally, but the former secretary of State remains the prohibitive favorite to win the Democratic presidential nomination, according to a new poll.

The Monmouth University survey released on Wednesday shows Clinton taking 51 percent support over Sanders's 17 percent. That’s a 9-point drop for Clinton since April and a 10-point gain for Sanders.

Sanders is drawing crowds of thousands of supporters on the trail, and his campaign has consistently had to move events to larger arenas. While Clinton still holds a big lead nationally, Sanders’s surge has been most pronounced in Iowa and New Hampshire, the first two states to cast ballots in 2016.

In a briefing with reporters in Washington on Tuesday, top Clinton aides acknowledged they expect a protracted nomination fight.

“This will be a fight for the Democratic nomination, and it will be hard to secure it,” said communications director Jennifer Palmieri. “There are a lot of people Hillary Clinton will need to convince to support her, and that’s what we expect will happen.”

The Monmouth poll indicated the contest could endure another jolt if Vice President Biden enters the race. He’s currently in third place, taking 13 percent support, but the survey found his standing would improve if he jumps in.

Twelve percent of Democratic voters said they would be very likely to support Biden if he enters the race, and another 31 percent said they would be somewhat likely to support him.

All told, 25 percent of Democratic voters said they would be very likely to support Biden, and more than 50 percent said they would be somewhat likely to support him.

The poll found that Biden’s support would draw from Clinton's: 68 percent of those who said they would be likely to vote for Biden are presently Clinton supporters.

“Most people seem to be focusing on a Sanders surge among the liberal wing of the party,” said Monmouth polling director Patrick Murray. “But the bigger threat to Clinton may come from a Biden candidacy, where the two would be fighting for the same voters.”

A majority of Democrats, 53 percent, say they would like to see Clinton face a competitive primary, with only 36 percent saying it would be better for Clinton to have a smooth path to the nomination.

Still, Clinton is in good shape. The survey found 74 percent of Democrats view her favorably. It’s the best favorability rating in the field.

Former Maryland Gov. Martin O’Malley is still struggling to gain traction. He is in fourth place, taking only 1 percent support. And just 27 percent of Democrats know enough about him to have an opinion.

The Monmouth University poll of 357 registered Democrats was conducted between July 9 and July 12 and has a 5.2 percentage point margin of error.