WASHINGTON (AP) - At least publicly, there's no hint of progress in efforts to avoid the "fiscal cliff" -- with Republicans demanding that the White House outline specific spending cuts, and the White House saying it's already done so.

But the rhetoric from the two sides has been relatively restrained, as if to avoid jeopardizing any negotiations that might be taking place.

And in fact, officials have disclosed that President Barack Obama and House Speaker John Boehner have exchanged at least partial proposals in the past two days, although details are scarce.

Boehner said publicly today that the White House was slow-walking the negotiations, bringing the economy closer to feeling the impact of the automatic spending cuts and tax increases that would kick in next month.

Meanwhile, House Democratic leader Nancy Pelosi challenged Boehner to allow a vote on Obama's proposal to extend most expiring tax cuts while letting those cuts expire at higher income levels.

Meanwhile, the nation's top corporate executives are stepping up pressure on Congress and on President Barack Obama to negotiate a deal to avoid a fiscal cliff, warning that failure will result in "significant negative economic, employment, and social consequences."

The CEOs, all members of the Business Roundtable, delivered letters to the White House and to congressional leaders urging a compromise that includes revenue, even if it means raising tax rates, and structural and benefit changes to social programs. Their letter says spending reductions must be a "multiple of increased revenues."

The 158 CEOs include Boeing Co.'s James McNerney, David Cote of Honeywell International Inc. and Jeffrey Immelt of General Electric Co.

Separately, top home building executives also wrote to Obama and House Speaker John Boehner calling for an agreement.

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