ANNAPOLIS -- A Maryland Senate panel approved a constitutional amendment Thursday that would make it much harder for politicians to use transportation money for anything else.

The measure would put a so-called lockbox on the Transportation Trust Fund, which is supposed to be used for roads, rails and bridges, but from which lawmakers have taken millions to use for other projects.

Under a lockbox, the governor would have to declare a fiscal emergency and a three-fifths supermajority of both legislative chambers would have to sign off for transportation money to be used for anything else.

The Senate Budget and Taxation Committee also approved Gov. Martin O'Malley's transportation funding bill, which includes a weaker lockbox provision that also requires fiscal emergency, but only a three-fifths committee vote to raid the Transportation Trust Fund.

Both bills now go before the full Senate.