There are new concerns about the ______ of the U. S. economic expansion.

Americans’ income growth effectively stalled in June, and consumer spending plunged at the steepest monthly rate since September 2001, the government reported yesterday, fueling new concerns about the strength of the U.S. economic expansion.
   Overall personal income was flat in June after adjusting for inflation and taxes, the Commerce Department said. Consumer spending dropped 0.7 percent in June, reinforcing other signs that the U. S. economic expansion lost momentum in the spring with rising inflation, higher interest rates and a slowing pace of job creation.
   The report comes as President Bush and Sen. John Kerry, the Democratic presidential nominee, continue to spar over the effectiveness of the administration’s economic policies. A series of tax cuts and Federal Reserve interest rate cuts helped boost economic growth for much of the past three years, but many analysts had expected stronger employment growth and income gains to fuel a more vibrant recovery by now.
   The June results "raise increasingly serious questions about the strength and sustainability of the economy in the months ahead," said Charles W. McMillion, president and chief economist of MBG Information Services.
   Stock prices fell and bond prices rose yesterday as many investors concluded that the economy may continue to cool, which would both reduce profit growth and ease inflation pressures.
   Federal Chairman Alan Greenspan said last month on Capitol Hill that the economy had hit temporary a "soft patch," but that it should not hinder an expansion that appeared to be broadening and gaining momentum. And he signaled that the Fed would likely raise rates gradually to keep inflation under control.