An acceleration in the pace of U.S. economic growth in the second half of this year is expected to ebb as 2012 gets underway, although the odds of another recession have receded to one-in-four, a Reuters poll showed on Wednesday.

Encouraged by a recent pick-up in economic data, the consensus from more than 60 respondents showed a better view on the final three months of the year and 2011 overall.

But the pace of is expected to wane from an annualized 2.5 percent in the third quarter, and growth is not expected to get back to that rate again until the final quarter of next year.

More fiscal restraint, uncertainty surrounding the euro zone sovereign debt crisis and lackluster consumer sentiment and spending are all seen taking some of the steam out of growth early next year.

We have positive momentum to carry us through to the early part of next year, but the headwinds are still going to cap the pace of growth, said Scott Brown, chief economist at Raymond James.

Apart from a raging euro zone sovereign debt crisis that has a chokehold on global financial markets and that is now gripping Italy, uncertainty over U.S. fiscal policy also clouds the outlook for the start of 2012.

A payroll tax holiday and federal unemployment benefit program are set to expire, while a special committee of lawmakers is meeting to reach a deal on reducing the federal deficit.

There are a number of things coming together with regards to fiscal policy that makes early next year look very iffy, said Mark Zandi, chief economist at Moody's Analytics.

CRAWLING GROWTH

Barring unforeseen shocks, economists believe the economy should avoid another recession, though growth will be slow.

Gross domestic product growth is seen at an annualized 2.3 percent in the fourth quarter, up strongly from the 1.9 percent forecast in the October poll. The Reuters consensus for the year was raised to 1.8 percent from 1.7 percent.

However, growth expectations for next year were revised down modestly, with a 1.7 percent expansion in GDP anticipated in the first quarter, down from earlier forecasts of 1.8 percent. The consensus for the second quarter slipped to 2.0 percent from 2.1 percent.

Economists appeared to have greater conviction about their 2012 GDP outlook as the difference between the highest and lowest projection fell to 2.0 percentage points from 3.2, the narrowest in a year.

While recent data suggests the euro zone could already be in recession, economists think the United States' economy should be able to weather a modest slowdown overseas.

I think they're already in recession, said Zandi. I think we can digest a mild European downturn, but not a severe one.

The median of economists polled found there was a 25 percent chance of another recession in the next 12 months. That was down from the 30 percent chance given in October, but the still-significant odds illustrate the fragility of the recovery.

However, three contributors still see at least one quarter of contraction over the forecast horizon, unchanged from one month ago.

Low inventories, high cash, low corporate debt, and already low employment would make it difficult to start a new recession from this point, said Marc Pado, U.S. market strategist at Cantor Fitzgerald & Co.

It would require a complete collapse of the European economy, which, while unlikely, cannot be ruled completely out of the question.

CPI was seen averaging 3.5 percent in the fourth quarter, up from earlier expectations of 3.3 percent, before easing to 2.7 percent in the first quarter. That estimate was still up from previous forecasts for 2.5 percent.

Core CPI -- which strips out volatile items such as food and gasoline -- was seen at 2.1 percent in the fourth and first quarters, easing from expectations of 2.2 percent for both.

(Polling by Namrata Anchan, Sarmista Sen and Snehasish Das; Editing by Catherine Evans)

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