Federal Reserve officials, meeting one last time under Alan Greenspan's guiding hand, are expected Tuesday to raise U.S. interest rates for a 14th straight time, while signaling uncertainty about the future.

The central bank's rate setting Federal Open Market Committee began meeting at 9 a.m. EST as scheduled, a Fed official said. A decision on interest rates is expected around 2:15 p.m., together with a statement on the U.S. central bank's analysis of economic conditions and the level of policy accommodation .

After their last rate rise on Dec. 13, policy-makers said higher borrowing costs would "likely" be needed and analysts are united in the view the Fed will push up overnight rates another quarter-percentage point to 4.5 percent.

Economists, however, look for a shift in tone in the Fed's description of the rate outlook to suggest an increase at the next meeting in late March is not a done deal.

Many Fed watchers think the central bank will ditch "likely" and simply say more rate hikes "may" be needed.

Others think the Fed may drop the guidance it has been offering since it began to push credit costs up in June 2004 and say simply that incoming data will drive its decisions.

The meeting may or may not mark the end of a 19-month long rate-rise campaign, but it will without question mark the end of Greenspan's 18-1/2 years in office.

The U.S. Senate is expected to confirm former Fed Governor Ben Bernanke as the next chairman during the day, clearing him to take office Wednesday.

"Our guess is that Greenspan will try to leave his successor with as clean a slate as possible, both in terms of policy buzzwords and in terms of implied policy guidance," Lou Crandall of Wrightson ICAP wrote in an analysis for clients.

When the Fed began to push up the overnight federal funds rate 19 months ago, it stood at a 1958 low of 1 percent. The benchmark rate is now at 4.25 percent, close to a level many economists say neither spurs nor weighs on economic activity.

"The easy part of the tightening cycle is behind us now and so you're at the point where more judgment is required," said Dana Johnson, chief economist at Comerica Bank in Detroit.

In futures markets, where bets are placed on the direction of interest rates, investors see about an 80 percent chance of another quarter-point tightening at the Fed's next meeting on March 28, the first gathering at which Bernanke will take the lead.

But the economic crosscurrents are far from clear, and Fed officials are expected to stress they will make their decisions based on incoming economic information.

The U.S. economy expanded at a meager 1.1 percent rate in the fourth quarter of last year, but inflation aside from volatile food and energy prices was running a bit faster than Fed policy-makers want.

However, so-called core prices edged up just 0.1 percent in December and have gained only 1.9 percent over the past 12 months, just within the Fed's perceived comfort zone.

While most economists expect the economy to rebound sharply this quarter from its surprisingly sluggish pace at the end of 2005, some expect a softening housing market to eventually take the wind out of the expansion's sales.

Merrill Lynch chief economist David Rosenberg points to declining prices for new homes as foreshadowing the weakening that may lie ahead.

"New home prices are deflating -- bye-bye mortgage equity withdrawal boom, which, by the way, helped underwrite almost 40 percent of the growth in consumer spending in the past three years," he said in a research note.