Sen. Virg Bernero, D-Lansing, might be the deciding factor in whether the Senate Republican leaders choose to try to override an abortion bill veto.

Senate Bill 395, better known as the legal birth definition act, defines exactly when a person is born as "when any portion of a human being has been vaginally delivered outside his or her mother's body."

Partial-birth abortion would be considered illegal in Michigan under this bill.

If Bernero is elected as the next mayor of Lansing in November, he will step down from his seat in the state Senate, leaving 37 members rather than the usual 38.

With Bernero gone, the number of votes needed to override Gov. Jennifer Granholm's veto would fall from 26 to 25. There were 25 senators who voted in support of the bill, including three Democrats.

The bill passed in the House by a vote of 74-28 in May. In the House, 74 votes are needed to override the veto.

Although the override is a possibility, it's still speculative whether the Senate will act, said Bill Nowling, spokesman for Sen. Ken Sikkema, R-Grandville.

Sikkema, the Senate majority leader, was one of the bill's many sponsors.

"It takes a lot of effort to fight a veto and to put that all together," Nowling said.

Recent polls have shown that incumbent Mayor Tony Benavides has a firm lead over Bernero in the race for Lansing's top spot.

Sen. Bob Emerson, D-Flint, the Democratic Caucus leader in the Senate, said it was too early to begin worrying about a possible override.

"I've heard these rumors floating around here," said Emerson, one of the 11 Democrats who opposed the bill. "I wish Virgil well in the mayor's race, but I hope we don't have to face this."

According to Emerson, the only reason there would be an attempt to override the bill would be to embarrass the governor.

"It seems like this Legislature is about to go through the federal government, so what we do about it here doesn't really matter," Emerson said.

And the bill's supporters might have ulterior motives, Emerson said.

"Every year we have some legislation where people try to redefine the most vogue issue in terms of the abortion debate," Emerson said. "All this nibbling around the edges is only really being used for political purposes."

If Bernero vacates, it will take at least three months to fill the empty spot, giving Senate Republicans plenty of time to act if they want to, Emerson said.

Granholm spokeswoman Liz Boyd said the decision is up to the Legislature, although Granholm continues to oppose it.

"The courts have held that there has to be a clear exception for the health of a woman, and this bill does not give that," Boyd said. "Certainly, we are always in touch with the Democratic members of the Legislature and they know the governor's feelings about this."