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Democratic presidential candidate Joe Lieberman (search) criticized President Bush on Wednesday for a sluggish economy that has kept Americans out of work.

The Connecticut senator said he would work toward ensuringU.S. productivity growth (search)  -- the amount of output per hour of work -- at 3 percent annually by the end of his first term.

The United States was mired in weak productivity from the early 1970s to the early 1990s, but the rates started to improve after 1995 to greater than 2 percent annually. Lieberman's goal of 3 percent growth would double the rates experienced for two decades before 1995 but is less than the 4.8 percent achieved last year.

The Lieberman campaign says recent productivity gains have been linked to rising unemployment, while his economic plan would focus on creating new jobs. He criticized Bush for the job losses, deteriorating economy and reduction of national savings.

"The administration of George W. Bush has pursued a Flintstones agenda in a Jetsons world," Lieberman said in remarks prepared for delivery at the University of California, San Diego, on Wednesday. "And in so doing, George Bush has let the sparks of innovation fall to the floor. As your president, I will make sure they spread to a much bigger, broader fire."

Rising productivity is a key determining factor for the economy's long term health and for living standards to increase. Lieberman said a sustainable 3 percent rate would double family incomes every generation.

Lieberman said he would reach his goal by passing tax cuts (search) that would spark productivity, restoring fiscal discipline, pushing a $40 billion increase in funding for research and development, supporting free trade and improving math and science education, among other measures.

Prior to delivering the speech, Lieberman picked up an endorsement from venture capitalist John Doerr, a leader in the high-tech field and a political heavyweight from the Silicon Valley, sources said.

As part of the northern California-based Kleiner Perkins Caufield & Byers, Doerr sponsored several major investments in such companies as Compaq, Amazon.com, Netscape and Sun Microsystems. Doerr advised Democrat Al Gore's campaign in 2000.