ANNAPOLIS, Md. Maryland officially became the first state in the nation Tuesday to approve a plan to give its electoral votes for president to the winner of the national popular vote, instead of the candidate chosen by state voters.

Gov. Martin O'Malley, a Democrat, signed the measure into law, one day after the state's General Assembly adjourned.

The measure would award Maryland's 10 electoral votes to the national popular vote winner. The plan would only take effect if states representing a majority of the nation's 538 electoral votes decided to make the same change.

Sen. Jamie Raskin, a law professor and sponsor of the idea, said Maryland is largely ignored by presidential candidates during campaigns, because they assume the Democratic state will vote for the Democratic candidate.

Raskin, a Democrat, said he hoped Maryland's support for the idea will start a national discussion and "kick off an

insurrection among spectator states -- the states that are completely bypassed and sidelined" during presidential campaigns.

"Going by the national popular vote will reawaken politics in every part of the country," Raskin said.

Other states are considering the change to avoid an election in which a candidate wins the national popular vote but loses in the Electoral College, as in 2000 when Democrat Al Gore lost to George W. Bush.

Hawaii's legislature recently passed a similar measure, sending it to Republican Gov. Linda Lingle. California lawmakers adopted the measure last year, but Republican Gov. Arnold Schwarzenegger vetoed it.

National Popular Vote, a group that supports the change, said there are legislative sponsors for the idea in 47 states. Ryan O'Donnell, a spokesman for the group, described O'Malley's decision to sign the legislation as "an open invitation" for other states to join Maryland.

"We're really filled with optimism that other states are going to see that this is not only a possible way to fix broken

elections, but a sound way," O'Donnell said.

But not everyone is buying into the idea. North Dakota and Montana rejected it earlier this year. Opponents say the change would hurt small rural states, where the percentage of the national vote would be even smaller than the three electoral votes they each have in the overall Electoral College.

Zach Messitte, a professor of political science and director of the Center for the Study of Democracy at St. Mary's College in Maryland, said the change would make candidates focus on highly populated areas, at the expense of smaller states that are protected by the current system.

"I personally don't think it's a great idea," Messitte said. "I think there are negatives to this, and I think it ignores this

broad historic sweep that at different times of American history, different parts of the country have their different moments in the sun."

Under the current Electoral College system, voters decide to support slates of "electors," who meet to choose the president. A candidate needs a majority of 270 out of 538 to be elected.