WASHINGTON - New York Mayor Michael Bloomberg, a potential independent candidate for president, has scheduled a meeting next week with a dozen leading Democrats and Republicans. They are expected to join him in challenging the major-party contenders to spell out their plans for forming a "government of national unity" to end the gridlock in Washington.

Others scheduled to be at the Jan. 7 session at the University of Oklahoma say that if the likely nominees of the two parties do not pledge to "go beyond tokenism" in building an administration that seeks national consensus, they will be prepared to back Bloomberg or someone else in a third-party campaign for president.

Conveners of the meeting include such prominent Democrats as former Sens. Sam Nunn of Georgia, Charles Robb of Virginia, David Boren of Oklahoma, and Gary Hart of Colorado, a former presidential candidate. Republican attendees are to include Sen. Chuck Hagel of Nebraska, former party chairman Bill Brock, former Sen. John Danforth of Missouri, and former New Jersey Gov. Christie Whitman.

Boren, who will host the meeting at the university, where he is president, said: "It is not a gathering to urge any one person to run for president, or to say there necessarily ought to be an independent option. But if we don't see a refocusing of the campaign on a bipartisan approach, I would feel I would want to encourage an independent candidacy."

The list of acceptances suggests that the group could muster the financial and political firepower to make the threat of such a candidacy real. Others who have indicated that they plan to attend the one-day session include William Cohen, a former Republican senator from Maine and defense secretary in the second Clinton administration; Alan Dixon, a former Democratic senator from Illinois; Bob Graham, a former Democratic senator from Florida; Jim Leach, a former Republican U.S. representative from Iowa; Susan Eisenhower, a political consultant and granddaughter of former president Dwight Eisenhower; David Abshire, president of the Center for the Study of the Presidency; and Edward Perkins, a former U.S. ambassador to the United Nations.

Bloomberg, a former Democrat who was elected mayor of New York as a Republican, left the GOP in the summer to become an independent. While disclaiming any plan to run for president next year, he has continued to fuel speculation by traveling widely and speaking out on domestic and international issues. The mayor, a billionaire many times over, presumably could pay for his candidacy even after a late start.

"As mayor, he has seen far too often how hyperpartisanship in Washington has gotten in the way of making progress on a host of issues," said Stu Loeser, Bloomberg's press secretary. "He looks forward to sitting down and discussing this with other leaders."

A letter from Nunn and Boren sent to those attending the Jan. 7 session said that "our political system is, at the least, badly bent, and many are concluding that it is broken, at a time where America must lead boldly at home and abroad. Partisan polarization is preventing us from uniting to meet the challenges that we must face if we are to prevent further erosion in America's power of leadership and example."

At the session, Boren said, participants will try to draft a statement on such issues as the need to "rebuild and reconfigure our military forces," combat nuclear proliferation and terrorism, and restore American credibility in the world.