WASHINGTON (CNN) -- House Minority Leader John Boehner, R-Ohio, sharply criticized on Thursday a new proposal by House Democrat's that calls for all U.S. troops out of Iraq by August 2008, saying it is "an old twist on an old adage."

"Unfortunately, the Democrats latest plan is an old twist on an old adage: failure at any cost," he said in a Capitol Hill press conference. "Democrats are using the critical troop funding bill to micromanage the war on terror -- undermining our generals on the ground and slowly choking off resources for our troops.

"By establishing and telegraphing to our enemy arbitrary timelines for withdrawal, democrats are mandating failure," he added.

Earlier Thursday Pelosi called the plan, which sets defined time tables, "will refocus our military efforts on Afghanistan and fighting the war on terrorism where it began."

Related: Democratic bill would have troops out of Iraq by fall 2008

-- CNN's Alexander Mooney and Hida Fouladvand