WASHINGTON — Amid increasing anxiety that the White House and top Republicans are wasting time as the government slides toward an economy-rattling "fiscal cliff," administration officials are heading to Capitol Hill for talks with congressional leaders.

Treasury Secretary Tim Geithner and senior White House aide Rob Nabors were to visit separately Thursday with the four leaders of the House and Senate to discuss how to avert a series of tax increases and spending cuts due to begin in January. Republicans complain that the White House is slow-walking the talks and has yet to provide specifics on how President Barack Obama would curb the rapid growth of benefit programs like Medicare and Medicaid.

There's been little evident progress in negotiations between the White House and the lead GOP negotiator, House Speaker John Boehner of Ohio. Boehner's lieutenants say the White House has been slow to engage.