Image caption Donald Trump won the biggest applause of the conservative conference's first day

US conservative political activists and Republican politicians - including potential presidential hopefuls - have gathered at a summit in Washington DC.

The Conservative Political Action Conference (CPAC) is an opportunity for possible 2012 candidates to test the waters and attract funding and support.

But one of the conservative movement's stars, Sarah Palin, declined to attend.

Meanwhile, celebrity mogul Donald Trump told the gathering he would decide by June if he was running for president.

In the gathering's opening address, outspoken conservative Congresswoman Michele Bachmann of Minnesota told those present: "You've already changed America."

Ms Bachmann, a prominent figure in the Tea Party movement, told delegates their mission was to defeat President Barack Obama in the 2012 presidential election.

Later, using language analysts say echoed a campaign speech, Mr Trump declared his opposition to legal abortion and support for gun ownership rights.

The star of the Apprentice television show declared "the United States is becoming the laughing stock of the world" and said US trading partners were "screwing us".

Intra-party strife

Former House Speaker Newt Gingrich, another potential presidential candidate, criticised what he described as Mr Obama's "war on American energy", and proposed replacing the US Environmental Protection Agency with an Environmental Solutions Agency he said would create jobs.

Image caption Sarah Palin said she was not attending the conference because of a scheduling conflict

Former Vice-President Dick Cheney's brief remarks were interrupted by protesters who shouted "draft dodger" and "war criminal".

And former Defence Secretary Donald Rumsfeld, who is promoting his memoir, Known and Unknown, said one lesson he had learned was that the US was the best country in the world.

Others at the conference include former Massachusetts Governor Mitt Romney, former Minnesota Governor Tim Pawlenty, Mississippi Governor Haley Barbour and Rick Santorum, a former senator from Pennsylvania and strong social conservative.

Ms Palin, one of the most popular and closely watched conservative figures in the country, did not attend, citing a scheduling conflict.

In a sign of intra-party strife that is likely to build as the party nomination fight heats up, Mr Santorum suggested Ms Palin was skipping the conference because she would not be getting paid.

But speaking on Fox News on Wednesday night, Ms Palin suggested Mr Santorum was "uninformed" and called him a "knuckle-dragging Neanderthal".

Straw poll

CPAC, which runs until Saturday, is billed as the largest gathering of conservatives in the US.

The conference concludes with the release of a straw poll of potential presidential candidates.

Analysts say the results are likely to have little bearing on the contest for the Republican nomination when it heats up - the first balloting will not happen until January next year.

But analysts say if none of the best known entrants comes out ahead, it could signal the conservative movement is unsatisfied with the current crop of contenders.

Delegates will have the opportunity to attend seminars on topics ranging from ways to break into the film industry to Tea Party study sessions, as well as a range of speeches by notable Republican lawmakers.