If John Kerry (search) is elected president, his seat in the Senate would be filled by the winner of a special election rather than a successor picked by Republican Gov. Mitt Romney (search) under a bill approved Wednesday by the Massachusetts Senate.

The Senate voted largely along party lines, 32-8, after a sometimes testy debate pitting the badly outnumbered Republicans, who opposed the change, against Democrats. The measure now goes to the Democratic-controlled House.

The bill requires a special election not more than 160 days and not less than 145 days after a vacancy is created in the Senate (search). Under the bill, a vacancy is created when a letter of resignation is filed, even if the incumbent senator does not actually resign until a later date. The winner of the special election would serve out the remainder of the unexpired term. Kerry's term ends in 2008.

Although Romney could veto the measure, the Democrats have the votes to overturn it.

Democrats argue that allowing the governor to appoint a successor is less democratic than a special election, even a quick election.

The governor said he supports having a special election, but he wants to give the candidates enough time — up to nine months — to raise money, hold a primary, debates and then stage a general election. In the meantime, Romney said, he should be allowed to appoint a replacement who could then run in the general election.

Romney has called on Kerry to resign his seat, arguing that he has paid little attention to his Senate duties while campaigning for president.