Washington (CNN) Bernie Sanders had a summer to remember, but as his campaign downshifts from the buzz of giant rallies to focus on the nuts and bolts of the campaign, it is struggling with that adjustment.

November also brings the harsh reality of dropping poll numbers, especially as Hillary Clinton's resurgence takes hold.

A look at his recent activities demonstrates the problems facing Sanders.

Sanders launched his first ad this week -- an intro spot with $2 million behind it in early states. But the man who consistently criticized poll-driven politicians also hired a pollster, former Howard Dean demographic guru Ben Tulchin, at the urging of top strategist Tad Devine and others, putting his campaign in the position of having to explain it as a hire meant to help guide the media buys.

"Here's where we are, literally today is the first day that we've had TV ads," Sanders told CNN Tuesday afternoon as he walked back to his Senate office. "Secretary Clinton has been in Iowa, New Hampshire for many months, she has spent $6 to $8 million. We have not spent a nickel before today. So now we're on and I expect we're gonna stay on. I think they're pretty good ads."

Thursday, Sanders will formally file for the ballot in New Hampshire, where his big lead over Clinton from this summer has dissipated. Normally that's an easy free media boost, but the Independent senator from Vermont could face a challenge if anyone questions his filing status as a Democrat. The Sanders campaign has said, however, they are confident he will make the ballot.

Friday, he will be in South Carolina for a Democratic forum hosted by MSNBC. He is planning to spend Saturday in Rock Hill, Columbia and Aiken before flying to Nevada Sunday.

But he faces a nearly impossible task in the Palmetto State: the latest polling there shows him getting walloped by Hillary Clinton 71%-15%, according to the latest Winthrop University Poll.

Next week he flies to Des Moines, Iowa for the second Democratic debate. There will be fewer candidates --- Jim Webb and Lincoln Chafee dropped out and Joe Biden decided not to run --- but he can't afford a repeat of the first debate where Clinton's strong performance moved the needle in the polls.

And sometime after that debate he is expected to explain precisely what democratic socialism means in a much-anticipated -- and much-touted by his campaign -- speech. But that speech has already been delayed -- it was originally promised to come before the debate.

Sanders says he's going to be a factor in the early states.

"In both Iowa and in New Hampshire, in South Carolina, in Nevada and in other states we're putting together pretty strong grassroots organizations," Sanders said. "We have been very successful in attracting nationally hundreds of thousands of people who are prepared to work on a campaign as volunteers, we're putting together good staffs to mobilize those volunteers. And you're going to see us playing, having a very aggressive ground game in those first four states."

His tone has also changed. The candidate who once promised not to go negative on his Democratic opponents surprised a crowd at the Iowa Jefferson-Jackson Dinner last month when he railed against Clinton for being a latecomer to liberal causes like opposition to global trade pacts.

"What campaigns are about is a contrast in points of view. And Secretary Clinton and I have different points of view on a number of very important issues, and I think the American people want to hear that discussion," Sanders said Tuesday. "We're just going to be making it clear what our views are and what Senator Clinton's are."

Clinton's big October may have something to do with Sanders' strategy. After her well-received "Saturday Night Live" cameo and strong debate performance, Clinton sat for 11 hours before the House Benghazi panel to positive reviews among Democrats.

New Hampshire Democrats are returning home to Clinton, said Patrick Murray, director of the Monmouth University Polling Institute. One event, he said, which helped bring them back was Clinton's rebuttal of Sander's "shouting" remark on gun control.

Sanders said during the first Democratic debate that he was tired of the "shouting" over gun control, but Clinton turned around after the debate and said "I'm not shouting. It's just that when women talk, some people think we're shouting."

"I think there's a whole host of things that coalesced at once," Murray said.

In the Senate -- where Sanders has yet to win an endorsement from any of his longtime colleagues and Clinton has hardly had to work for the almost three dozen she's gathered -- Clinton supporters are already looking past the fight.

"I'm not going to comment about Bernie's strategy as he tries to be more competitive with Secretary Clinton. I just want to make sure that we all come together when this is over," said Sen. Claire McCaskill, a Missouri Democrat and outspoken Clinton surrogate.

Struggles with African-American voters

Sanders also acknowledges he has work to do in South Carolina. He may have been consistently packing arenas in college towns and throughout the Northeast, but the South is one region which has definitely not felt the Bern.

The latest Winthrop University Poll, which showed Clinton dominating Sanders, offered one of the clearest reasons: he has yet to win over African-American voters. Of the respondents, Clinton won 10 times as much support from African Americans as Sanders 80% to 8%. She also dominated him in every other subgroup -- including white voters, men and women voters -- but the gap was largest among African Americans.

Clinton has made a strong play to solidify her support in the African-American community this week, meeting with the families of victims of gun violence, including the mother of Trayvon Martin. Sanders still has not been able to break through.

"One of our major hurdles is introducing myself to the African-American community," Sanders said Tuesday.

"I'm very proud of the very strong record that I have on civil rights, one of the strongest records in the United States Congress," Sanders said. "And I think the agenda we are offering, both in terms of criminal justice reform and in terms of economic, an economic agenda that benefits low and working class people will be an agenda that the African-American community will be responsive to. Our job now is to get it out, and that is precisely what we're working on. So we got a lot of work to do there, but I think we're going to be OK."