* Month-end buying cited as money managers adjust portfolios * Fed's commitment to bond purchases supportive * GDP bullish for bonds, jobless claims data bearish By Ellen Freilich NEW YORK, Feb 28 (Reuters) - U.S. Treasuries rose on Thursday as the potentially growth-damping impact of prospective U.S. government spending cuts fed the bid for safe-haven U.S. debt. Month-end buying as money managers adjusted their average portfolio duration to meet benchmarks was also supportive. So was reassurance from Federal Reserve Chairman Ben Bernanke this week that the U.S. central bank believed in the usefulness of its unconventional monetary easing strategies and that its bond purchases would continue. Two reports, one on the U.S. economy's growth in the fourth quarter and the other on the new jobless claims count for the week ended Saturday, were essentially neutral for bonds. The government said U.S. GDP grew 0.1 percent in the fourth quarter of 2012. That was less than the very modest 0.5 percent growth the market had expected. New claims for unemployment insurance, however, totaled 344,000, fewer than the 360,000 claims economists had forecast. "There was very little reaction in the bond market to this morning's data," said Tom DiGaloma, managing director at Navigate Advisors in Stamford, Connecticut. "Jobless claims dropped significantly, but the revisions to GDP showed growth in the fourth quarter was still quite weak." The benchmark 10-year Treasury note was up 5/32, its yield easing to 1.89 percent from 1.90 percent late on Wednesday. SEQUESTER AHEAD President Barack Obama and Republican congressional leaders have yet to reach a deal to avert the $85 billion worth of spending cuts known as the "sequester" which economists say will hurt the economy. Strategists say the cuts, or protracted negotiations over them, supported demand for low risk government debt. Thirty-year Treasury bonds rose 13/32 in price, their yields easing to 3.08 percent from 3.10 percent late on Wednesday.