Gov. Martin O'Malley (D) signed a bill into law today that makes Maryland the first state in the nation to join a movement to bypass the Electoral College and elect U.S. presidents by national popular vote.

The bill, passed in a session of the General Assembly that concluded yesterday, would award the state's 10 electoral votes to the presidential candidate who wins the most votes nationwide -- not statewide. The agreement would not take effect until states that cumulatively hold 270 electoral votes -- the number needed to win a presidential election -- sign on.

Supporters of the measure, which is being championed by a national nonprofit group, say deciding elections by popular vote would give candidates reason to campaign nationwide and not concentrate their efforts in "battleground" states, such as Florida and Ohio, that have dominated recent elections.

Moreover, the supporters argue, such a system would prevent rare occasions, such as President Bush's 2000 victory over Al Gore, in which a candidate who wins the popular vote does not prevail in the electoral college, a fixture in U.S. elections since the nation's founding.

During debate, opponents argued election by popular vote could just switch the target for candidates from closely divided states to large cities with many voters -- a scenario that would not necessarily empower Maryland. And they suggested a national recount could be chaotic.

The bill was among more than 100 signed by O'Malley in the first of four ceremonies scheduled in coming weeks. Other legislation established a sub-cabinet to coordinate the impact of the national Base Realignment and Closure process on Maryland and set up a government accountability program called StateStat.

Most of the higher-profile legislation that passed late in the 90-day session will be signed at future ceremonies. The session ended last night.

"This was a successful session," O'Malley said at the outset of the ceremony. "This is a session where we found consensus in order to advance the common good."