WASHINGTON (Reuters) - Federal Reserve Chair Jerome Powell and Vice Chair Philip Jefferson will make what are likely to be their last public comments before the U.S. central bank's next meeting, as they try to reconcile a gravity-defying economy with their assessment that monetary policy is "restrictive" and inflation likely on its way down.

Both of those ideas have been called into question by job growth, retail spending, inflation and other data that continue to challenge the Fed's expectation as the year began that the economy was gliding towards lower demand, slower growth, and price increases nearing the central bank's 2% target.

Powell just over five weeks ago told a U.S. Senate panel the Fed was "not far" from gaining the confidence in falling inflation needed to cut interest rates, but policymakers, investors and outside analysts have lost a bit of faith in that outlook since.

In the days just after Powell's congressional testimony, futures contracts tied to the Fed's policy rate reflected an initial quarter-percentage-point rate cut as likely to occur at the central bank's June 11-12 meeting, with two more reductions in borrowing costs by the end of 2024. Now the first cut is seen in September, and the odds of even a second cut were falling after the U.S. government reported on Monday a 0.7% rise in retail sales in March that exceeded expectations in a Reuters poll of economists.

Economists at Goldman Sachs raised their estimates of first-quarter economic growth to a 3.1% annual rate, from 2.5%, after that report, while others saw it as another reason for the Fed to keep its benchmark policy rate unchanged.

"This is another clear sign of the resilience of the U.S. consumer, which we think will keep growth strong this year and adds to the risks that the Federal Reserve will delay its first rate cut beyond June," Michael Pearce, deputy chief U.S. economist at Oxford Economics, wrote in a note. "We still expect Fed officials to lower rates later this year, but that will be justified by renewed signs of moderating inflation later this year, rather than fears the economy is about to weaken dramatically."

Powell and Jefferson will have an opportunity to update where they think things stand in comments that begin with a 9 a.m. EDT (1300 GMT) speech by Jefferson, followed by Powell fielding questions alongside Bank of Canada Governor Tiff Macklem at 1:15 p.m. (1715 GMT). Both events are in Washington.

'LAST MILE'

"Patience" is likely to remain the watchword.

When inflation was in fast decline last year, Powell was reluctant to declare the fight against it won, though the Fed did indicate the 5.25%-5.50% range was as high as the policy rate needed to be, and laid the groundwork for rate reductions beginning this year.

Officials at the Fed's March 19-20 meeting said they still expected to cut the policy rate by three-quarters of a percentage point by the end of 2024. Powell at the time said disappointing inflation data in January and February "haven't really changed the overall story, which is that of inflation moving down gradually on a sometimes-bumpy road toward 2%."

Yet the bumps continue, enough so that some officials at the March meeting worried that monetary policy was not having the sort of impact that would be typically expected from the highest interest rates in a quarter of a century.

Data since then has shown a massive 303,000 jobs were added in March, the pace of consumer price increases accelerated, and even low-income households continued to spend.

The strength of the economy, policymakers suggest, is one reason they could wait to cut rates and be sure inflation will resume its decline.

New data on the personal consumption expenditures price index, which the Fed uses to set its inflation target, will be released next week, and could show some slight improvement for policymakers to take into their April 30-May 1 meeting.

But even optimists aren't expecting a big improvement, if there is any at all.

"This question of the last mile is a little harder," with progress slowing as the Fed gets closer to its inflation target, Chicago Fed President Austan Goolsbee said on Friday. "If we see that inflation is on this path back down to 2%, then ... do we want to remain as restrictive as we are right now for a prolonged period? If inflation doesn't come down. That answers it for us."