President Reagan plans to use the Jefferson Memorial as a backdrop today for a speech on an "Economic Bill of Rights" that, among other things, would require proposed bills to be accompanied by "financial-impact statements."

White House officials briefed reporters in three waves yesterday, trying to build interest in an economic package that includes such familiar Reagan advocacies as a constitutional amendment requiring a balanced budget and allowing presidential vetoes of individual spending items.

A senior official who insisted on anonymity said one feature of the package is a proposal requiring a "super-majority" congressional vote for any tax increase -- either three-fifths or two-thirds. In 1981, Sen. William L. Armstrong (R-Colo.) offered a constitutional amendment to accomplish this, but the proposal has languished in Congress.

The official said Reagan's message will be less partisan in tone than recent speeches on the subject and is "not designed to take on Congress."

However, congressional Democrats moved to upstage the president by criticizing Reagan's speech before delivery and offering their own proposals.

House Speaker Jim Wright (D-Tex.) said it is "ironic" that Reagan would use the Jefferson Memorial for his address since "Jefferson, the champion of the common man, would have been shocked at the insensitive priorities and grossly excessive borrowing of the Reagan administration."

Reps. Charles A. Hayes (D-Ill). and Augustus F. Hawkins (D-Calif.) proposed an "Economic Bill of Rights" calling for "the right to useful paid employment, a decent home, a good education, protection from the economic fears of old age and adequate medical care."

Reagan's call for a financial-impact statement modeled after environmental-impact statements required by law has been termed a "truth-in-spending" measure by White House officials. They said the president's speech will also include renewed appeals for deregulation and "privatization" of the economy.

The president is scheduled to fly by helicopter to Camp David for the holiday weekend immediately after delivering his speech this morning. In his weekly radio speech Saturday, he is expected to call for confirmation of Judge Robert H. Bork's nomination to the Supreme Court.