In a little more than 60 days, voters will choose the men and women who will represent them in Congress. There are two questions every voter should ask of each candidate.

First, if elected, do you promise to fulfill your constitutional responsibilities as a member of a separate, independent and equal branch of government?

Second, if elected, do you promise to work in a bipartisan manner, open to cooperation with members of the opposing political party?

There was a time when neither question would have had to be asked. Members of Congress understood that they had obligations imposed by the Constitution and that those obligations trumped any allegiance to party or president. For example: When Democratic President Franklin D. Roosevelt attempted to pack the U.S. Supreme Court with justices more favorable to his programs, the plan was opposed by his own vice president, John Nance Garner, and defeated by an overwhelmingly Democratic Congress. Roosevelt's War Department was investigated by a Democratic senator, Harry S. Truman. Decades later, when Democratic President Carter proposed cutting spending on federal water projects, he was rebuffed by a Democratic Congress. And when Republican President Reagan proposed a tax increase, the opposition was led by Republican House members.

In each case, members of Congress were willing to stand up to a president of their own party to do what they thought was right. Contrast that with the current feeble congressional response — from both parties — to President Bush's claims of expanded presidential authority and his administration's clear contempt for the legislative branch.

In a parliamentary system, power rests with the executive, and the legislative majority functions in a supporting role. But the U.S. Congress is intended not to be a rubber stamp but a check on presidential power and the principal architect of national priorities.

As the "first branch" of government, Congress has all legislative authority and is charged with determining what the law shall be and how much, if anything at all, is to be spent for any proposed project.

Yet when Bush thumbs his nose at Congress — declaring his authority to disregard legislation, permitting agency officials to lie to Congress and to walk out of hearings, ignoring clear statutory requirements — members of Congress mumble and pout and do nothing.

Congress is fading into irrelevance, and it is up to the voters this fall to demand of their prospective representatives whether they intend to perform their constitutional duties.

The second question to legislators is equally important. One reason given for Democratic opposition to Connecticut Sen. Joe Lieberman in this month's primary was his failure to be a "team player." Lieberman's willingness to find common ground with Republicans was seen as disloyalty.

The bitter polarization about which so many observers complain is not merely ideological; it is partisanship carried to an extreme. Instead of morphing from candidates to members of Congress on the day they are sworn in, today's legislators engage in permanent campaigns. Neither party is willing to allow the other to gain credit for an achievement that might help it in the next election, so the center aisle that divides Democrats from Republicans in the House has become a wall.

But there comes a time, after the votes are counted, when being American trumps being a member of a particular political party.

The issues facing this nation are difficult and complex. For examples, one need look no further than immigration or the problems of energy dependence. There is a pressing need for members of the House and Senate, regardless of party, to work together to find solutions both sides can agree on. Voters should insist that they do.

Candidates for the House and Senate will be making urgent appeals to the voters for the next two-plus months. During that time, citizens can make a few appeals of their own. One is for a Congress that recognizes its responsibilities and takes them seriously. And if they do not get satisfactory assurances, citizens can withhold their votes. Complaining is not enough; it is time for voters to demand a Congress that does its job.

Mickey Edwards teaches at Princeton University's Woodrow Wilson School of Public and International Affairs. He wrote this commentary for the Los Angeles Times.