The people of the District of Columbia moved a step closer Thursday to gaining voting rights they have been denied for more than 200 years.

But the legislation passed by the House on a 241-177 vote faced a veto threat from the White House, which said it was unconstitutional.

The bill would permanently increase full House membership to 437, giving the largely Democratic half-million residents of the district a seat and adding a temporary at-large seat for Republican-leaning Utah. The House has consisted of 435 seats since 1960.

The House still needed to approve an accompanying tax bill before the legislation could be sent to the Senate, where its fate was uncertain. Senate Republican leader Mitch McConnell, R-Ky., echoing the position of the Bush administration, said it was unconstitutional and he would oppose it.

"This legislation corrects a serious flaw in our democracy," said House Speaker Nancy Pelosi, D-Calif. "We will not rest until full voting representation in the House is granted to the District of Columbia."

Democrats had to pull a nearly identical bill from the floor a month ago after Republicans surprised them by proposing language, with a good chance of passing, that would have lifted the district's ban on semiautomatic weapons and other tough gun restrictions. This time, over strong protests from Republicans, Democrats came prepared with a floor procedure blocking a gun vote.

Under that procedure limiting GOP options for changing the bill, the House was separately taking up a small tax-raising bill to pay for the cost of elections in the district.

Opponents of the legislation pointed to Article I, Section 2 of the Constitution, which says members of the House should be chosen "by the people of the several states."

"Judges and legal experts agree that since D.C. is not a state, it cannot elect members of Congress," said Rep. Lamar Smith, R-Texas, top Republican on the Judiciary Committee.

Supporters, led by the current Washington delegate to the House, Eleanor Holmes Norton, argue that the Constitution, in empowering Congress to "exercise exclusive legislation" over the federal capital, does give Congress the authority to give the district full voting rights.

Her Republican partner on the bill, Virginia Rep. Tom Davis of Washington's suburbs, said District of Columbia residents had paid taxes with other Americans this week and had served in every war. He urged other Republicans to "see through the fog of armchair constitutional analyses and do the right thing."

Currently, Norton can vote in committee and on some amendments but not on final passage of any bill. Republicans questioned whether the bill would allow the district to keep its delegate, with limited voting rights, along with a new representative with full rights.

The idea of giving a seat to Washington was dormant during the past 12 years when Republicans controlled the House, but it was the Republican Davis who came up with the idea of coupling the D.C. seat with a temporary at-large seat for Republican-leaning Utah.

Utah, which now has three representatives, narrowly missed out on attaining a new seat after the 2000 census and reapportionment.

The House would remain at 437 after the 2010 census, when Utah, because of population growth, is in position to gain a new fourth district. The legislation would not change the makeup of the Senate, where the District of Columbia has no representation.

Congress approved a constitutional amendment in 1978 giving the district a vote in the House, but the amendment died after failing to get ratification by three-fourths of the states. In 1993 the House rejected a proposal to put the district on the road to statehood.

D.C. residents have had the right to vote in presidential elections since the 23rd Amendment was ratified in 1961.