A House of Representatives panel dominated by Republicans has voted overwhelmingly to block a Dubai-owned firm from taking control of some US port operations.
The House Appropriations Committee voted 62-2 to bar DP World, run by the United Arab Emirates government, from holding leases or contracts at US ports.
The landslide vote was the strongest signal yet that more than three weeks of White House efforts to stunt congressional opposition to the deal have not been successful.
President Bush has promised to veto any such measure passed by Congress. But there is widespread public opposition to the deal, and the Republican Party fears losing its advantage on the issue of national security in this autumn's elections. The White House said the president's position was unchanged.
"This is a national security issue," said Republican Jerry Lewis, the chairman of the House panel, adding that the legislation would "keep America's ports in American hands".
As the committee acted, Democrats on the other side of the Capitol manoeuvred for a vote in the Republican-led Senate.
Republican leaders are trying to block a vote on the ports deal through a procedural vote that could occur as early as today. The tactic is likely to fail, which could prompt Republicans to pull a lobbying reform bill from the floor to avoid defeat on the ports measure.
AP