Washington — Just before Vice-President George Bush took the podium, a congressional aide edged over to the press corps and asked a question that put in perspective President Reagan's July 19 rally in support of a constitutional amendment to balance the budget.
''Is Channel 39 here?'' he asked quietly. ''Congressman (Duncan) Hunter wants to know.''
The rally, conducted on the west steps of the Capitol in sweltering heat, was a carefully crafted media event intended to pressure Congress by going over its head, to the voters - a tactic used with devastating effect to help pass last year's tax and budget cuts.
President Reagan, in his speech supporting the proposed constitutional amendment to balance the budget, said, ''The people are saying, no more ifs, ands, buts, or maybes. We want a constitutional amendment to balance the budget, and we want it now.''
The proposed constitutional amendment to balance the budget would require Congress each year to adopt a balanced budget, unless three-fifths of both chambers voted otherwise. In addition, the US government's tax receipts could not increase faster than national personal income, unless Congress passed specific tax increases.
Supporters say these requirements, linked together, would stop the tendency of government spending to constitute an ever-growing share of the economy. Critics claim the measure is unenforceable, and will lead to congressional deadlock instead of a balanced budget.
Organized by the White House, the unusual rally in support of the measure marked the first time President Reagan has appeared at a public function on the Capitol steps since his inauguration in January 1981. Balanced budget amendment supporters said the hoopla was Reagan's way of pressuring Congress to act on the issue.
''He's doing what he does best - communicating,'' says William Shaker, executive vice-president of the National Tax-Limitation Committee. Shaker likened the rally to the President's televised speeches of last year, which were widely credited with helping push tax and budget cuts through Congress.
''This is a way for (Reagan) to add his own personality to the issue,'' says an aide to a Senator who intends to vote for the resolution.
This public demonstration of White House support comes at a crucial time for the balanced budget amendment. The bill will come to a vote on the Senate floor either late this week or early next. Supporters say they have 61 firm votes; 66 are needed to pass a proposed constitutional change. Congressional sources say Reagan's public proclamation may convince enough wavering senators to push the amendment through the chamber.
In the House, the balanced budget measure is bottled up in the Judiciary Committee. Last week, Rep. Barber Conable (R) of New York filed a discharge petition to pry the amendment loose from the grasp of the committee's chairman, Rep. Peter Rodino (D) of New Jersey. As of July 19, the petition had 104 signatures, says an aide to Conable. Two hundred eighteen House members must sign the petition if it is to be successful. Soon after the President's appearance on the west side of the Capitol, opponents of the amendment staged a counter-demonstration on the other side of the Hill.
''President Reagan and the Congress are simply finding it a beautiful way to distance themselves from the deficit,'' says Theresa McKenna, communications director of the National Council of Senior Citizens, the group organizing the protest.