State Representative Daniel B. Winslow, a former judge and onetime aide to Governor Mitt Romney, said Thursday he is entering the special election for the US Senate, the first Republican to officially declare his candidacy. 
 
 “I’m in,” Winslow said in a telephone interview. He had said earlier this week that he was “99 percent” certain he would run. 
 
 Winslow said he has donated $100,000 of his own money to jumpstart his campaign, which he estimated will cost between $4 million and $6 million. 
 
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 On Monday, he said, he is flying to Washington to meet with Republicans on Capitol Hill and with the National Republican Senatorial Committee, which controls much of the party’s national fundraising. Nex month, Winslow said, he will resign from his law firm, Proskauer, where he is senior counsel in the litigation department. 
 
 “I’m going to be 100 percent running for the US Senate,” Winslow said. “This is a heavy lift. I’m going to give this race everything I’ve got.” 
 
 Winslow, 54, is a second-term state representative from Norfolk who served as Romney’s chief legal counsel from 2001 to 2005. Before that, he was a district court judge. 
 
 “I have a proven record of respect for Second Amendment constitutional freedoms,” Winslow wrote in an email announcing his candidacy to party activists and supporters. “My experience as a fiscal conservative and problem solver is experience we need in Washington DC. Our future depends on getting this right.” 
 
 Many of the bigger-name Republicans, including former senator Scott Brown, former governor Wiliam F. Weld, and former lieutenant governor Kerry Healey, have taken themselves out of consideration. 
 
 Other Republicans considering the race include Senate Minority Leader Bruce E. Tarr, former congressional candidate Sean Bielat, and Gabriel E. Gomez, a private equity investor and former Navy SEAL. Jon Fetherston, a former chair of the Ashland Board of Selectman, is also planning to run for the seat. 
 
 Two US House members, Stephen F. Lynch and Edward J. Markey, are running on the Democratic side. 
 
 To qualify for the April 30 ballot, candidates will have to gather 10,000 certified signatures by Feb. 27. That hurdle may weed out many of the little-known candidates who cannot raise substantial sums of money. Winslow said he plans to use volunteers and paid staff to collect signatures and has no doubt he can make the ballot. ||||| State Rep. Daniel B. Winslow became the first Republican to officially join the U.S. Senate special election to replace Secretary of State John F. Kerry yesterday, saying he is “110 percent” committed to what will be a short but potentially bruising race. 
 
 “I’m going to give this everything I’ve got, with all that I have, because the crisis confronting our country demands nothing less,” Winslow (R-Norfolk) said. “I am confident I am going to be on the Republican ballot.” 
 
 Winslow is the first Republican to officially enter the race after Democratic U.S. Reps. Stephen F. Lynch and Edward J. Markey announced they were running. Gabriel Gomez, a Cohasset businessman, and state Senate Minority Leader Bruce E. Tarr (R-Gloucester) are also mulling a run. 
 
 Tarr said he will make a decision as to whether he is in or out of the race “no later than Monday.” 
 
 Joining the special election has become increasingly difficult with every day that passes because candidates must collect 10,000 signatures before Feb. 27 to get on the ballot. 
 
 Winslow, who launched an exploratory committee Tuesday, said he is confident he can get all the signatures, even though candidates usually must collect up to 20,000 signatures in case some aren’t accepted. 
 
 “We’re going to use a combination of paid vendors and an army of volunteers to get this done,” said Winslow, who once served as former Gov. Mitt Romney’s chief legal counsel. 
 
 Republicans have been scrambling to find a candidate since former U.S. Sen. Scott Brown announced last Friday that he isn’t running. ||||| Scott Brown, who surprised the political world with his upset victory in the 2010 special election, announced Friday afternoon that he will not enter the special election to replace John F. Kerry. 
 
 “I was not at all certain that a third Senate campaign in less than four years, and the prospect of returning to a Congress even more partisan than the one I left, was really the best way for me to continue in public service at this time,” Brown said in a statement. “And I know it’s not the only way for me to advance the ideals and causes that matter most to me.” 
 
 Brown’s announcement was unusual. Rather than a formal press conference or statement, he initially released the news to the Boston Herald in a text message that said “U are the first to know.” His spokesman later confirmed the news to the Globe in a text that read “Not running.” 
 
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 The full statement was released later. 
 
 Brown’s decision leaves the Republican Party scrambling to find a viable candidate for the June 25 election. To make the ballot, candidates must gather 10,000 certified signatures in four weeks. 
 
 Brown had long been considered the party’s strongest and most likely candidate. The party may now turn to former governor William F. Weld or former lieutenant governor Kerry Healey. 
 
 Beyond that, the list of credible candidates is thin. Weld has left open the possibility he would run, but associates say he is unlikely to leave his law and consulting practice to resume a political career. 
 
 Healey has not ruled out a run, but has said she was hoping that Brown would be the nominee. 
 
 Other possible Republican candidates Gabriel Gomez, a businessman and former Navy SEAL from Cohasset, and State Representative Daniel Winslow, a former district court judge who has served in the Romney administration and has higher political aspirations. 
 
 State committeeman Steve Aylward said his fellow activists are upset that Brown bowed out immediately after his chosen chairman was elected to lead the party. Kirsten Hughes only narrowly won the chairmanship Thursday night, after a big push by Brown to get her elected. 
 
 “One of the reasons for voting for Kirsten was that Scott Brown was running for Senate and needed her to be there,” said Aylward, who supported Hughes’ opponent. “Now one day afterward, he decides not to run for it? I think I’m speaking for a lot of the grassroots activists who are going to say, ‘this doesn’t pass the smell test.’ ” 
 
 Brown, in his statement, thanked voters and reflected on his three-year tenure in the Senate, but gave no hints about his future plans. 
 
 “When I was first sent to the Senate in early 2010, it wasn’t exactly welcome news for President Obama or many other Democrats,” he said. “Yet among my best memories from those three years in office are visits to the White House to see the President sign into law bills that I had sponsored. I left office last month on the best of terms with colleagues both Republican and Democrat. I had worked well with so many of them, regardless of party, to serve the public interest just as we are all supposed to. All of this was in keeping with the pledge I made at the beginning to do my own thinking and to speak for the independent spirit of our great state. 
 
 Two Democrats, US Representatives Edward Markey and Stephen Lynch, are vying for their party’s nomination. 
 
 Lynch, who is trying to appeal to the same moderate and conservative blue collar voters that Brown captured, released a statement about Brown’s decision before Brown’s even went out. 
 
 “I understand Scott Brown’s decision,” Lynch said. “He has basically been campaigning non-stop for three years. It’s perfectly understandable that he wouldn’t want to undertake another campaign. I wish all the best to Scott and his family.” 
 
 The Globe reported today that Washington Republicans had mounted a “full court press” to persuade Brown to run. 
 
 The effort, coordinated by the National Republican Senatorial Committee, came as those familiar with Brown’s thinking were becoming concerned that he would not run and would instead seek a job in the private sector. 
 
 The national GOP’s pitch to Brown was that he was at the height of his popularity and had a campaign and fund-raising structure still in place from his unsuccessful race against Elizabeth Warren. 
 
 But Brown had told state Republicans and others in his circle that he was exhausted from his campaigns in 2010 and 2012. He has noted to friends that if he won the election, he would have to gear up for a fourth campaign in 2014 to win a full term. 
 
 Brown may yet enter the race for governor in 2014. Republicans have generally fared better in races for state office than in races for federal office in Massachusetts. 
 
 After losing the November election to Elizabeth Warren, Brown had dropped several strong hints that he would run again for the Senate.
– After being rebuffed by Scott Brown, Tagg Romney, William Weld, and Kerry Healey, Massachusetts Republicans finally have at least one candidate for Senate. State Rep. Daniel Winslow, who had previously said that he was "99% certain" he'd run, yesterday told the Boston Globe he was "going to be 100% running for the US Senate." Winslow chipped in $100,000 of his own money to start the campaign, but that's a fraction of the $4 million to $6 million he estimates the venture will cost. Before becoming a state rep, Winslow served as chief legal counsel to Mitt Romney and as a district court judge. He'll fly to Washington on Monday to meet with the National Republican Senatorial Committee, presumably in the hopes of securing more funding. At least three other Republicans are also publicly considering runs, but every day they delay getting in will make that prospect harder, the Boston Herald points out, because candidates need 10,000 signatures by Feb. 27—and generally shoot for 20,000 in case some are challenged.