WASHINGTON  The chairmen of President Obama’s debt-reduction commission have been unable to win support from any of the panel’s elected officials for their proposed spending cuts and tax increases, underscoring the reluctance of both parties to risk short-term political backlash in pursuit of the nation’s long-term fiscal health.

The chairmen of the commission  former Senator Alan K. Simpson, a Republican, and Erskine B. Bowles, a Democrat and former chief of staff to President Bill Clinton  delayed for two days, until Friday, a final vote by its 18 members.

They said the delay was to provide more time to look at the final package, but it also gave them further opportunity to woo some of the 12 members of Congress on the commission, six from each party, whose support will be critical if the plan is to be taken seriously as a blueprint for eventual legislation.

The commission pressed ahead with its last-ditch efforts as Mr. Obama and Republican leaders opened negotiations on Tuesday in search of what the president called “sensible common ground” in their debate over extending the Bush-era tax cuts. It is the most immediate domestic issue facing them and a key test of whether the two sides can work together in the new political order.