UPDATE 1-US Congress may push immigration over climate bill

* Immigration debate could squeeze out climate control

* Either initiative faces uphill fight this year

* Election-year politics play into Senate formula

(Adds quote from Pelosi spokesman in paragraph 5)

By Richard Cowan and Thomas Ferraro

WASHINGTON, April 21 (Reuters) - Democratic leaders in the U.S. Congress may try to win passage of contentious immigration reform legislation this year in a move that could further harm prospects for a climate-change bill, congressional aides said on Wednesday.

House of Representatives Speaker Nancy Pelosi, Senate Majority Leader Harry Reid and other Democratic leaders huddled in the Capitol on Tuesday to discuss legislative priorities in what is rapidly becoming a tight schedule this election year.

During the meeting, Pelosi and Reid discussed which bills the Senate might be able to pass this year, according to one House Democratic leadership aide. The aide said that Pelosi told Reid "if you can do immigration first, that's fine."

"It was all about what they (the Senate) can get done," added the aide, who asked not to be identified.

Drew Hammill, a spokesman for Pelosi, said she was "fully committed to getting a comprehensive energy and climate bill" passed this year.

An immigration debate could dominate the Senate for several weeks or months, whether or not it comes to a final vote. This could occur at the very time that proponents of climate-change legislation had hoped the Senate focus would be on their bill.

The immigration reform legislation aims to toughen border security and update the process for admitting temporary workers while also providing a path for citizenship for the 11 million people in the United States illegally, most of them Hispanics.

Tens of thousands of people rallied last month in Washington to demand immigration reform.

Climate-control legislation aims to bring the United States into a global effort to reduce emissions of so-called greenhouse gases blamed for global warming.

Both bills are seen as long-shots for passage this year.

Another senior House Democratic aide, who asked not to be identified, said that both Pelosi and Reid talked about the importance of passing immigration reform this year.

"I don't remember there being a real conversation" on climate legislation during Tuesday's meeting, the aide added.

Jennifer Duffy, who tracks Senate races for the non-partisan Cook Political Report, said turning to immigration reform next would rev up the liberal Democratic base, as well as the conservative Republican base in opposition.

'TIME TO DO IT'

With Hispanic groups clamoring for a fresh push on immigration reform, Reid must decide which bill to focus upon after the Senate finishes landmark financial industry reforms.

Reid himself is facing a difficult re-election bid in November in his home state of Nevada. At a rally this month in Las Vegas, Reid noted that Congress had just wrapped up a "Herculean effort" on healthcare reform and said "now it's time to do it all over again" on immigration reform.

Hispanics were key to President Barack Obama winning Nevada in the 2008 presidential election and may determine if Reid wins a fifth six-year term in the Senate in November.

With no action in Congress on immigration since Obama took office, the Democratic Party is fearing a political backlash from Hispanics, who largely vote Democratic.

But making immigration reform the next priority could be at odds with Obama, who last week said he thought energy and climate-change legislation should take center stage after Congress finishes the upcoming financial reform debate.

Senator Lindsey Graham, a Republican point man on both immigration and climate control, told reporters that the Senate was not prepared to debate immigration reform this year.

"I think we ought to take it up next year with the new Congress," Graham said.

Asked why Reid is now pushing it, Graham said, "I think it's because he is in an election and he has a big Hispanic vote, and they (Democrats) made promises" to revamp immigration laws this year.

It is unclear what would happen to the climate-change legislation if Reid turns to immigration reform, Graham said.

The House already has passed climate-control legislation. The Senate is awaiting the unveiling, scheduled for Monday, of a compromise measure being written by Graham along with Democrat John Kerry and independent Joseph Lieberman.

Environmentalists hope the climate bill takes center stage in June or July, a time frame seen as a last chance this year for its passage.

Many Republicans have criticized the climate-change measure that forces electric power utilities, refineries and factories to reduce their carbon emissions, which come from burning fossil fuels, as little more than a national energy tax.

Democrats control the House and Senate by large margins, but fear that their majority could be greatly diminished after November's elections in which all 435 House seats are up for grabs along with 36 of 100 Senate seats.

(Editing by Will Dunham)