Bernie Sanders is gaining ground and Hillary Clinton is losing it in the two early-voting states of New Hampshire and Iowa, according to the September NBC News/Marist polls centered on the race for the Democratic U.S. presidential nomination in 2016. The surveys indicate the U.S. senator from Vermont is leading the former secretary of state in New Hampshire by 9 percentage points among potential voters while closing the gap between himself and the front-runner in Iowa by more than one-half since July.

In New Hampshire in September, Sanders had the support of 41 percent of Democratic voters and Clinton had the support of 32 percent of them. That disparity stands in stark contrast to the NBC News/Marist poll results in July, which showed Clinton with 42 percent support and Sanders with 32 percent support.

Meanwhile, the support of an undeclared candidate, Vice President Joe Biden, rose to 16 percent in September from 12 percent in July. When voters were asked to remove Biden from their considerations, Sanders’ support rose to 49 percent and Clinton’s rose to 38 percent.

“What the polls seem to indicate is Hillary Clinton’s support is receding a bit. We’ve got a long way to go. Joe would be a formidable opponent,” Sanders told NBC News.

Formidable, indeed. In Iowa, Clinton is leading among Democratic voters, but both Sanders and Biden captured more support in September than they did in July. Most recently, Clinton had 38 percent, Sanders had 27 percent and Biden had 20 percent. Previously, Clinton had 49 percent, Sanders had 25 percent and Biden had just 10 percent.

Although voters may be increasingly attracted to Biden or perhaps just losing faith in Clinton, the vice president himself has wavered about entering the race for the White House again. He ran for the Democratic nominations in 1988 and 2008. “Unless I can go to my party and the American people and say that I’m able to devote my whole heart and my whole soul to this endeavor, it would not be appropriate,” Biden said at an event in Atlanta last week.

On the other side of the political aisle, businessman Donald Trump leads among the 17 Republican contenders with significant gains in both states, according to the NBC News/Marist polls. Trump’s support now polls at 29 percent in Iowa and 28 percent in New Hampshire. In each case, retired Dr. Ben Carson is the runner-up with 22 percent in the former state and 11 percent in the latter state.

Wisconsin Gov. Scott Walker faced the largest drop-off on the GOP side, dropping 14 percentage points in Iowa and 8 points in New Hampshire. In July, the candidate had the lead in Iowa.