It was not enough, it seems, for Alan Greenspan, the former Federal Reserve chairman and a self-described lifelong Republican libertarian, to call for stringent government regulation of giant banks, as he did a few months ago.

Now Mr. Greenspan is wading into the most fierce economic policy debate in Washington — what to do with the tax cuts adopted, in large part because of his implicit backing, under President George W. Bush — with a position not only contrary to Republican orthodoxy, but decidedly to the left of President Obama.

Rather than keeping tax rates steady for all but the wealthiest Americans, as the White House wants, Mr. Greenspan is calling for the complete repeal of the 2001 and 2003 tax cuts, brushing aside the arguments of Republicans and even a few Democrats that doing so could threaten the already shaky economic recovery.

“I’m in favor of tax cuts, but not with borrowed money,” Mr. Greenspan, 84, said Friday in a telephone interview. “Our choices right now are not between good and better; they’re between bad and worse. The problem we now face is the most extraordinary financial crisis that I have ever seen or read about.”