Rep. Gary Peters (D-Mich.) officially announced Wednesday he'll run for Michigan's open Senate seat, casting himself as an "independent voice" intent on cleaning up the "mess" in Washington.

"Today — I am officially announcing that I am a candidate for the U.S. Senate in 2014. This is a critical time for Michigan, and our main streets and middle class need an independent voice fighting for them," Peters said in an email to supporters early Wednesday afternoon. 

"Washington is a mess, but Michigan is on the verge of reinventing itself with a new economy and a middle class that's stronger than ever — and I want to be on the front lines of that fight," he said.

The congressman has been expected to run for weeks and will likely have little opposition in the Democratic primary to replace longtime Sen. Carl LevinCarl Milton LevinSen. Gillibrand, eyeing 2020 bid, rankles some Democrats The Hill's 12:30 Report Congress needs bipartisanship to fully investigate Russian influence MORE (D-Mich.), who announced his retirement earlier this year.

He'll make his first appearance of the campaign later this afternoon in his hometown of Rochester Hills, Mich., where his family has lived for generations.

The three-term congressman has proven to be a tough campaigner over the years. He defeated an incumbent in a suburban swing district by a large margin in 2008 and held on in 2010 despite the GOP wave. After Republicans eliminated his district in redistricting, he went into Detroit and easily won a primary over Rep. Hansen Clarke (D-Mich.), making him one of just two white Democrats in the country to represent an African-American majority district.

Peters has been expected to run since Levin announced his retirement and has been gearing up for a campaign, raising more than $370,000 in the last three months. He has more than $800,000 to start for the race.

Michigan Democratic power broker Debbie Dingell's decision last week not to run after some behind-the-scenes elbowing between the two cleared the final obstacle for Peters to have a clear primary.

Peters told The Hill he has a good relationship with Dingell and her husband, Rep. John Dingell (D-Mich.), and downplayed any tension.

“I've talked to Debbie. She's a personal friend as well as John. They've been friends for years,” he said.

The congressman, who already has the backing of nearly every statehouse Democrat, said he’ll be endorsed by Rep. Dan Kildee (D-Mich.) at a Thursday event. 

He made it clear he’s not worried about a primary challenge, and is already focusing on promoting his independent image and appealing to centrist voters.

"I've always believed that the things middle class families struggle with around their kitchen tables should define my work in Washington," he said. "Set politics and party aside: If it’s not right for Michigan’s small businesses and middle class, it’s never been right with me. I think that kind of independent approach is exactly what Michigan needs in the Senate right now."

He repeated those points in an interview, saying he’d heard the same concerns when he was representing his old district, which was whiter and more suburban, and his current Detroit-based district. 

“People want someone focused on getting the job done, not political talking points but rather solving problems,” he said. “I take very seriously the notion that you have to get out in your community; you have to talk to people but, more importantly, you have to listen to people.”

Republicans hope to make this race competitive. 

Most view Rep. Mike Rogers (R-Mich.) as their best chance to win the seat, though he is still weighing his options. If he doesn't run, former Michigan Secretary of State Terri Lynn Land (R) is also looking at a bid. Rep. Justin AmashJustin AmashWe need more congressional oversight on matters of war Some doubt McCarthy or Scalise will ever lead House GOP McCarthy faces obstacles in Speaker bid MORE (R-Mich.) has also shown interest, though establishment Republicans are fearful he could scare off other candidates and that his libertarian streak might not play well in a general election.

Peters declined to weigh in on the GOP field.

“I don't think a lot about whoever the Republican opponent will be,” he said.

This isn't Peters's first statewide run: In 2002 he lost a tight race for attorney general.

The National Republican Senatorial Committee highlighted the loss in a statement earlier this week.

"Gary Peters already lost a statewide campaign, and that was before supporting a cap-and-trade energy tax policy that would effectively put Michigan out of business and ObamaCare, which will raise healthcare costs," said NRSC spokesman Brad Dayspring. "It takes a special kind of guy like Peters to ask for a promotion from the very same people that his policies would put out of work."

Peters fired back in an interview with The Hill.

“I support comprehensive energy policy. We have to have energy independence. I find it interesting they're bringing it up again. That tells me they don't have anything better to say than bring up the same worn-out arguments. I heard the same thing in 2010 about that vote, talked about the need to make America strong and a diverse energy base, and even in a horrible year …  I was reelected,” he said. 

“The Republicans are going back a few years, and if that's the best they have, it shows how out of touch they are with the American people and the people of Michigan.”

The GOP needs to pick up a net of six seats this election to win control of the Senate. Their top targets are the seven Democrat-held seats in red states, but if the party can widen the playing field by making competitive an open seat in Michigan or Iowa, it will have a much better shot at winning back control.

This story was updated at 12:50 p.m. and 6:15 p.m.