WASHINGTON — The archivist of the United States said Wednesday that he’ll quickly certify as part of the Constitution an amendment banning midterm pay raises for Congress. But the issue is still far from settled.

Forty states passed the amendment between 1789 and this week, but congressional leaders said Congress should decide whether a ratification that takes 202 1/2 years counts.

Majority Leader George J. Mitchell has asked the Senate legal counsel for advice about the issues posed by the unprecedented case, press secretary Diane Dewhirst said Wednesday.

A day earlier, Mitchell and Minority Leader Robert Dole had signed a resolution by Sen. Robert Byrd, D-W.Va., that would be a vehicle for Senate action.

None of them said whether they think the amendment is valid. Their action asserts Congress’ power to have the final say.

“Congress — not the courts and not the executive — has the final say over whether an amendment has received the required votes for ratification in a reasonable time,” said Byrd. “It is now our obligation to give the most serious consideration to the significant issues involved.”

House Speaker Thomas S. Foley also said hearings are needed to clear up questions about the amendment, which was written by James Madison and sent to the states in 1789 without a ratification deadline.

A 1939 Supreme Court decision said amendments must be ratified within a reasonable time, but left it to Congress to decide how much time the states should have.

Modern-day amendments have had seven-year deadlines. The proposed Equal Rights Amendment had a seven-year limit, later stretched to 10 years.