BOSTON -- Massachusetts residents are voting in a Senate primary Tuesday where for the first time in a half a century, a Kennedy is not on the ballot.

Six candidates are hoping to fill the seat of Sen. Edward Kennedy, who died in August after battling brain cancer.

An aide to Kennedy's widow, Vicki, said she called all four Democratic candidates to wish them well in the primary election. Two Republicans are vying for votes, as well.

Democratic front-runner Martha Coakley and her husband voted at an elementary school in Medford. She started the campaign the earliest of all the candidates.

"It's really in the hands of the voters now, so, we're going to watch closely now but I think we've done everything we could," she said.

U.S. Rep. Michael Capuano voted in Somerville. With mild public interest in the race and a moderate turnout of anywhere from 10 percent to 25 percent predicted, he said it will all come down to which candidate is most successful in getting voters to go to the polls.

Democrat and City Year founder Alan Khazei voted in Brookline with his wife and two young daughters. He hoped his grassroots effort can overcome the odds of "better known candidates."

Democrat Stephen Pagliuca thanked his supporters after voting near his Weston home. After spending more than any other candidate to build visibility in the race, the Celtics co-owner said he felt confident he had a good shot at winning.

Republican state Sen. Scott Brown voted in Wrentham and then hit the phones to call supporters.

Republican candidate Jack E. Robinson worked the commuter crowd outside of South Station, using a bagpipe player to draw attention.