Bipartisan majorities in both the House and the Senate are backing gun owners in a landmark Supreme Court case.

The court next month will hear arguments in a challenge to the District of Columbia's ban on handguns, the most important gun rights case at the Supreme Court in 70 years.

Fifty-five senators and 250 representatives have signed onto a brief that urges the justices to strike down the ban and assert that the Second Amendment gives individuals the right to own guns for their protection.

"The Supreme Court has the perfect case to affirm ... a Second Amendment right to own a gun for self-defense," Sen. Kay Bailey Hutchison, R-Texas, said at a Washington news conference Thursday.

Nine Democrats in the Senate and 68 in the House joined much larger Republican contingents in signing the brief, which is expected to be filed Friday.

The main issue before the justices is whether the Second Amendment protects an individual's right to own guns or instead merely sets forth the collective right of states to maintain militias.

The Bush administration also supports individual gun rights. But the administration said governments still may impose reasonable restrictions on gun ownership and asked the justices to send the case back to lower courts without deciding whether the handgun ban fails that test.

Hutchison and Sen. Jon Tester, D-Mont., who also signed the brief, agreed that some restrictions are valid but said the court should declare the handgun ban unconstitutional and set a clear limit beyond which governments may not go to restrict gun ownership.