The House overrode President Bush's veto Thursday of a bill authorizing $2.6 billion for Amtrak and expanding the Interstate Commerce Commission's authority to review some railroad sales.

The Senate, which also must override the presidential veto for the bill to become law, began considering the legislation late Thursday. The Senate vote was expected to be closer than the 294-123 margin in the House.Two-thirds of the voting members of both chambers are needed to override the president's objections.

The railroad sale provision has turned the Amtrak authorization bill into an important test of administration strength in Congress.

The president said he vetoed the bill last month because it gives the ICC sweeping new powers to interfere with the marketplace and block some railroad sales.

"The provision would have required for the first time, and for the railroad industry alone, government review and approval of acquisitions of entities that are not actual or potential competitors, including a carrier's own management or employees . . . ," the president said in a letter to House Republicans Thursday.

The president said the commission already has enough authority to scrutinize railroad sales, adding, "there is no justification for creating such a serious regulatory roadblock to financial restructuring of the railroad industry."

Democrats say the railroad sale provision merely closes a loophole in the ICC's authority.

Current law is unclear, but the commission generally believes it can review the sale of a railroad only if the line is sold to another railroad. Individuals or companies not in the rail business may acquire all or part of a railroad without commission review.

The ICC provision in the Amtrak bill would expand the agency's authority to review acquisitions by groups not now covered.

Rep. Thomas Luken, D-Ohio, said the ICC provision "merely ensures that the proposed purchase of a major railroad is given a quick 'once-over' to see if the railroad will be used merely as a cash cow to be milked at the public's expense."

Amtrak's service would not be halted if the veto is sustained because the passenger railroad is operating on previously appropriated money.

The bill, however, also contains language that would save Amtrak some $17 million in unemployment insurance payments.

The president Thursday said he would support an Amtrak authorization bill that was stripped of the ICC provision. But Rep. John Dingell, chairman of the House Energy and Commerce Committee, said there is little time left in the current congressional session to approve another bill.

"The obstacles to the passage of such new legislation are legion," he said in a letter to Senate Commerce Committee Chairman Ernest Hollings, D-S.C.