BOSTON -- Massachusetts Attorney General Martha Coakley has achieved yet one more goal in her methodical quest for the late Sen. Ted Kennedy's Senate seat, coasting to a seemingly effortless Democratic primary victory Tuesday over her nearest competitor, U.S. Rep. Michael Capuano.

"They said women don't have much luck in Massachusetts politics and we believed that luck was about to change, and change it we did tonight," Coakley told a crowd of cheering supporters in Boston.

"You helped me convince the voters to send a different kind of leader to Washington," she said, crediting the political action group Emily's List for its help in the win. The organization works to elect pro choice, progressive female candidates.

If she were to win the seat, the career prosecutor would be the first woman elected to the U.S. Senate from Massachusetts.

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Coakley, 56, won this fall's short but expensive primary battle for the Democratic nomination, grabbing nearly 50 percent of the votes cast in her party's primary to win the chance to run for the seat Kennedy held for close to 50 years.

Capuano came in second place with about 28 percent of the primary vote. Just before 9:30 p.m. he conceded the race, saying Democrats should now throw their collective weight behind the Medford prosecutor.

"We're gonna work hard to make sure she's successful. It's important to all of us," Capuano told a roomful of cheering supporters.

"What we did was amazing," he said of his efforts to build a campaign organization in the few short months since Kennedy's death. In the end, however, he said, they just couldn't catch up to Coakley, who had a running start in the race.

"We couldn't narrow the gap," Capuano said. "Name recognition matters."

Coakley's Republican opponent, state Sen. Scott Brown, 50, was the projected winner in his primary, beating Jack E. Robinson for the GOP party's nod. (Read Brown's Story)

During the primary, Coakley went up against well-funded adversaries, including Celtics co-owner Stephen Pagliuca, City Year co-founder Alan Khazei and Capuano.

Pagliuca and Khazei ran a distant third and fourth, with Pagliuca getting 13 percent of the vote and Khazei 12 percent.

Pagliuca congratulated Coakley on running "a fantastic race," and said he would work hard to help send her to Washington. He jokingly added in his concession speech that he might still win in another arena.

"The Celtics are playing, so hopefully we'll be one for two tonight," Pagliuca said wryly.

Khazei also said he would throw his weight behind Coakley, saying "she will be a tremendous senator."

The Kennedy family also issued a statement commending Coakley.

“We want to congratulate Martha Coakley for tonight’s victory in the Massachusetts Democratic Senate primary and we have every confidence that she will be victorious in January’s general election as well. We believe that Martha Coakley will represent the people of Massachusetts with honor and deep commitment," the statement said.

Through the three-month campaign, Coakley's name recognition as a longtime Bay State politico and her well-established list of donors from prior campaigns made the state's top law enforcer the candidate to beat.

In September alone, Coakley raised almost $2.2 million while Capuano had to transfer $1.2 million from his U.S. House re-election account to supplement the $343,000 he raised that month.

Khazei, who also had a network of deep-pocketed donors, managed to raise $1.1 million in September according to a report filed with the Federal Election Commission.

Coakley, however, had a well-oiled campaign organization that had long worked for this prime opportunity. Throughout the race, she garnered the support of numerous law enforcement groups and organized labor groups, also targeting women voters and abortion rights supporters.

Beginning her legal career in 1979, Coakley practiced civil litigation with two private Boston law firms before joining the Middlesex District Attorney’s Office in 1986, as an Assistant District Attorney in the Lowell District Court office.

She worked for a time as a special attorney on the Boston Organized Crime Strike Force and later ran the Child Abuse Prosecution Unit for the district attorney's office. She was elected district attorney in 1998 where she oversaw the prosecution of several high-profile crimes, including the cases of several Catholic priests charged with sexually abusing children.

Coakley received a B.A. degree, cum laude, from Williams College in 1975, and a J.D. degree from the Boston University School of Law in 1979. She lives Medford with her husband, Thomas F. O’Connor, Jr.

Kennedy died of brain cancer in late August at age 77 after holding his seat since 1962.

The primary winners will face off in a general election on Jan. 19.