Rep. Ed Markey (D-Mass.) is running for the seat expected to be vacated by Sen. John Kerry (D-Mass.) upon his confirmation as secretary of state, the Boston Globe reports Thursday.

"I have decided to run for the U.S. Senate because this fight is too important," Markey said in a statement to the Globe. “There is so much at stake."

Markey is the first major candidate to announce a run, while Reps. Mike Capuano (D-Mass.) and Stephen Lynch (D-Mass.) have also signaled interest in running. Defeated Sen. Scott Brown (R-Mass.) has not said what he will do, but would be a strong candidate in a special election given his personal popularity.

Markey, 66, is the longest-serving congressman in the state's delegation, having been elected to the House of Representatives in 1976. He represents suburbs north and west of Boston. He ran for Senate in 1984 and withdrew from the race, and considered a run after the death of Sen. Ted Kennedy (D-Mass.).

Massachusetts Gov. Deval Patrick (D) said he will in all likelihood appoint a caretaker to the seat to take Kerry's place, while a special election would probably occur in early in June.

Markey's office did not return a request for comment Thursday.

UPDATE: Markey released a statement Thursday night announcing his run:

Like everyone in Massachusetts, I want to express my deepest appreciation to John Kerry for his remarkable service in the United States Senate. I know he will make a terrific Secretary of State.

“In the last election, the country -- and our Commonwealth -- voted for a better, more prosperous future for the middle class. But as we enter the New Year, it seems we are fighting the same old Republican Party.

“With Senator Kerry’s departure, Massachusetts voters will decide once again whether we want a Senator who will fight for all our families or one who supports a Republican agenda that benefits only the powerful and well-connected.

“The events of the last several weeks -- from the devastation of Hurricane Sandy and the tragedy at Sandy Hook Elementary to the fiscal cliff debate over tax giveaways to the rich, have all made clear that Massachusetts needs a Senator with the right priorities and values.

“I have decided to run for the U.S. Senate because this fight is too important. There is so much at stake.

“I refuse to allow the Tea Party-dominated Republican Party to lead us off the fiscal cliff and into recession. I won’t allow the NRA to obstruct an assault weapons ban yet again. I will not sit back and allow oil and coal industry lobbyists to thwart our clean energy future or extremists to restrict women’s rights and health care.

“There is a better way. We need to invest in innovation and jobs, so that everyone in Massachusetts can achieve the American Dream for themselves and their families. And we must protect Social Security and Medicare so that every American can retire in dignity. We need a sane approach to guns and violence. We need to a national policy that makes our country energy independent and curbs the pollution that is causing global warming and fueling extreme weather events like Hurricane Sandy.

“We need a Senator who will work with President Obama, and anyone else, to move our country and our Commonwealth forward.

“I look forward to traveling to every corner of the Commonwealth and meeting with the people who make Massachusetts so great.”

Also on HuffPost:

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  • President Barack Obama

    <blockquote>Today, I spoke to Ambassador Susan Rice, and accepted her decision to remove her name from consideration for Secretary of State. For two decades, Susan has proven to be an extraordinarily capable, patriotic, and passionate public servant. As my Ambassador to the United Nations, she plays an indispensable role in advancing America’s interests. Already, she has secured international support for sanctions against Iran and North Korea, worked to protect the people of Libya, helped achieve an independent South Sudan, stood up for Israel’s security and legitimacy, and served as an advocate for UN reform and the human rights of all people. I am grateful that Susan will continue to serve as our Ambassador at the United Nations and a key member of my cabinet and national security team, carrying her work forward on all of these and other issues. I have every confidence that Susan has limitless capability to serve our country now and in the years to come, and know that I will continue to rely on her as an advisor and friend. While I deeply regret the unfair and misleading attacks on Susan Rice in recent weeks, her decision demonstrates the strength of her character, and an admirable commitment to rise above the politics of the moment to put our national interests first. The American people can be proud to have a public servant of her caliber and character representing our country.</blockquote>

  • Sen. John Kerry (D-Mass.)

    “I've known and worked closely with Susan Rice not just at the UN, but in my own campaign for President. I've defended her publicly and wouldn't hesitate to do so again because I know her character and I know her commitment. She's an extraordinarily capable and dedicated public servant. Today’s announcement doesn't change any of that. We should all be grateful that she will continue to serve and contribute at the highest level. As someone who has weathered my share of political attacks and understands on a personal level just how difficult politics can be, I've felt for her throughout these last difficult weeks, but I also know that she will continue to serve with great passion and distinction.”

  • Sen. Lindsey Graham (R-S.C.)

  • Sen. John McCain (R-Ariz.)

    "Senator McCain thanks Ambassador Rice for her service to the country and wishes her well," the senator said in a statement from his spokesman.

  • Sen. Kelly Ayotte (R-N.H.)

    “I respect Susan Rice’s decision and appreciate her commitment to public service,” Ayotte says in a statement. “However, my concerns regarding the terrorist attack in Benghazi go beyond any one individual. I remain deeply troubled by the continued lack of information from the White House and the State Department. With four of our public servants murdered, it is critical that we get to the bottom of what happened.”

  • Rep. Barbara Lee (D-Calif.)

    “I am profoundly disappointed that Ambassador Rice, such a well qualified woman of color, would be denied the opportunity to become our next Secretary of State due to the baseless and manufactured allegations of the radical right. “I have known and worked closely with Ambassador Susan Rice for many years—on many global issues. From the genocide in Sudan to the ongoing violence in Syria, the humanitarian crisis in Haiti and the global HIV/AIDS crisis. Ambassador Rice works each and every day to advance the highest ideals of our country and would have been an outstanding Secretary of State.”