You can't put it much more simply than this:
President Barack Obama wants to sell world leaders on his ideas for sustaining global economic growth. One reason that won't be easy: He hasn't yet convinced the U.S. Congress.
Liberals want a big mid-year stimulus to spare state budgets from massive cuts and extend unemployment benefits and tax cuts. Moderates and conservative are asking for "offsets" to slash the 10-year price tag under $100 billion. Business leaders are complaining that the offsets will kill jobs. So there's your rock, and there's your hard place. Still Obama officials are saying things like: "Leadership by example is part of what we bring to the G-20..."
What example, exactly? The Senate is twisted into a pretzel over this bill and Reid has requested that financial reform wrap up before the weekend, nearly assuring that Obama's stimulus plug before the G20 will be a thesis without support.