Just days after a New Hampshire poll showed Hillary Clinton slipping further behind Bernie Sanders in the vital early primary state, a fresh survey shows the Vermont senator narrowly edging ahead of her in Iowa as well.

The Quinnipiac University poll shows Sanders leading Clinton 41-40 percent.

The results are well within the margin of error and represent a virtual tie in the first-in-the-nation caucus state. But together, the polling in New Hampshire and Iowa indicates Clinton's front-runner status is now being challenged in the primary season's two lead-off contests.

"Obviously the campaign is delighted," Sanders Press Secretary Lilia A. Chacon said in a statement. "People and Iowans are responding to a message based on issues. The more people know about Bernie the more they like him."

The Clinton campaign is stressing that they always thought this would be a "close race."

"No non-incumbent candidate other than Sen. Harkin has gotten more than 50 percent in the [Iowa] caucus -- which is why we are working hard to earn every vote," a campaign official said in an email, while touting Clinton's growing ground game in the Hawkeye State.

Despite the latest set of polls, Clinton continues to lead by a comfortable margin in national surveys.

The Iowa contest also is more than four months away. And even if Clinton lost the two lead-off contests, she could soldier on in other early-voting states like South Carolina and gather the delegates needed. She leads by double digits in virtually every poll in South Carolina, and in Florida.

But as with other recent polls, Sanders' rise underscores a potential vulnerability for Clinton who for months was the unquestioned front-runner but lately has faced growing questions about her personal email controversy.

While other rivals -- like former Maryland Gov. Martin O'Malley and former Virginia Sen. Jim Webb -- have failed to catch fire with voters, Sanders is gaining ground and Vice President Biden is still weighing a Democratic bid. The latest Quinnipiac poll suggests the VP has a built-in base of support; in Iowa, 12 percent said they back Biden.

And Sanders' 41 percent marked a major jump from a July survey by the same polling outfit. At the time, Sanders had 33 percent, to Clinton's 52 percent.

The Iowa poll follows an NBC/Marist survey Sunday showing Sanders with a 9-point lead in New Hampshire.

Sanders himself downplayed the daily drip-drip of polling results.

Asked about the Quinnipiac survey on Thursday, Sanders said, "Polls are polls -- today there is one poll, tomorrow there is another poll."

The Quinnipiac poll of 832 likely Iowa Democratic caucus-goers was taken Aug. 27-Sept. 8. It had a margin of error of 3.4 percentage points.