Environmental campaigner Al Gore is struggling to find a venue for his US climate change rock concert Live Earth.
Al Gore's film warns of the impact of humans on climate change
The former US vice-president wanted to hold the concert, one of eight global events, at Washington DC's Capitol Hill, home of the US Congress.
But Senate Republican Leader Mitch McConnell has objected because the proposal to use Capitol grounds has not been reviewed by the Senate.
Another US city is now being discussed. The concerts will take place on 7 July.
"While it's unfortunate for the American people that we are being blocked from staging the US concert in our nation's capital, the show must go on, even if it's in another city," said Chad Griffin, a senior adviser for Live Earth.
The original plan was to hold the gig at the National Mall in the US capital, but it was already in use.
The Red Hot Chili Peppers are set to perform at Live Earth
The resolution to hold the concert on the Capitol's West Lawn was proposed by Senate Democratic Leader Harry Reid and Republican Senator Olympia Snowe.
However, individual senators are able to block legislation.
Republican Senator James Inhofe has also opposed the move, although he has not formally blocked it.
"Senator Inhofe objects to having any events on the Capitol grounds that are either highly partisan or politically controversial - and the proposed Gore concert is both," said his spokesman Marc Morano.
Senator Inhofe has referred to global warming as "a hoax" in the past.
Washington DC Mayor Adrian Fenty still hopes the concert will take place in the city.
"We hope that things are resolved so that Mr Gore can have his event and promote his environmental initiative," said his spokeswoman, Mafara Hobson.
Gore is the author of An Inconvenient Truth, about the threat of global warming and potential solutions of the problem.
It was adapted for the screen and won two Oscars, for best documentary and best original song.
More than 100 of the world's top musicians will perform at the Live Earth concerts, which aim to highlight the threat of global warming.
The Red Hot Chili Peppers, Kanye West, the Black Eyed Peas, Bon Jovi, and Snow Patrol are among the acts set to perform around the globe, in cities including London, Shanghai and Johannesburg.