The British band Coldplay, along with Nine Inch Nails co-founder Trent Reznor, Rosanne Cash (Johnny Cash's daughter) and Rage Against the Machine's Tom Morello will join the effort via Twitter, linking up with a number of liberal groups, human rights groups and veterans organizations.

Approximately 20 veterans of the wars in Iraq and Afghanistan will be visitng Capitol Hill Thursday to make the case to lawmakers.

Meanwhile, on Twitter, the campaign said its aim is to make the Gitmo closure the number one trending topic (or most popular discussion subject) on Twitter today.

The organizers, New Security Action and Vote Vets, say that the campaign coincides with the one-year anniversary of President Barack Obama's pledge to close Gitmo within a year of taking office.  Obama acknowledged this fall that the stated timeline would not be met, although he said closing the controversial detention center remains a goal of his administration.

Here is a tweet from Coldplay:

RT @AmnestyUK Let's join @amnesty at 3pm GMT and help shine a light on the missed deadline for closing Guantanamo, by tweeting #closegitmo

The liberal group MoveOn tweeted:

It's time to #closegitmo. Support the Vets in Washington today urging Congress get it done. RT and spread the word.