Massachusetts lawmakers to vote on Kennedy seat

 BOSTON, Sept 17 (Reuters) - Massachusetts lawmakers will start voting on Thursday on whether to change state law to let an interim senator temporarily fill the late Edward Kennedy's U.S. Senate seat as the battle over healthcare rages.

The Democratic Party, which is loath to leave a crucial U.S. Senate seat vacant during the healthcare debate, overwhelmingly controls the Massachusetts legislature.

But deep divisions among local Democrats over allowing the governor to name a temporary replacement for Kennedy suggest the bill will only pass in the state House with a narrow margin. It could need a day or more to get through the state Senate as Republicans threaten to use stalling tactics.

"I think there's going to be enough votes," said Robert DeLeo, speaker of the state House of Representatives. "It's going to be probably closer than other votes that we have here but ... I think it will pass."

The legislation would let Massachusetts Governor Deval Patrick pick a temporary successor to Kennedy within days, keeping his seat from staying vacant between now and a Jan. 19 special election to fill it until 2012.

A towering figure in the U.S. Senate for nearly half a century, Kennedy made healthcare reform his signature issue.

His death in August from cancer deprived the Democrats of a crucial 60 votes in the U.S. Senate as President Barack Obama tries to overhaul the $2.5 trillion healthcare system.

The Massachusetts bill stipulates that an interim senator would have to be from the same political party as the person he or she replaces. A separate resolution would bar the appointee in this case from running for the permanent seat in January.

Some state Democrats worry that public opinion opposes what amounts to reversing a law barring state governors from naming senate replacements which they drew up in 2004 to prevent a Republican governor from appointing someone to Senator John Kerry's seat had he won the presidential election.

They fear a move that will benefit the party short-term will alienate voters ahead of January's special election.

Yet weighing on them is the risk of leaving Obama short of the Senate majority he needs to thwart Republican blocking maneuvers on a healthcare overhaul he wants to pass this year. (Reporting by Kevin McNicholas and Catherine Bremer; Editing by Cynthia Osterman)