Washington, January 14 (Reuters-RHC) - Several U.S. Republican senators proposed legislation on Tuesday that would place a moratorium on the release of most of the prisoners held at Guantanamo Bay, Cuba, saying they posed too much danger to the United States and its allies.

"It's clear that we need a 'time out' so that we do not re-confront the terrorists that we had captured and are currently in Guantanamo," said Senator Kelly Ayotte from New Hampshire.

Ayotte pointed out the legislation would put a two-year moratorium on the transfer of "medium- and high-risk detainees" from the facility, which she said were the overwhelming majority of the 127 prisoners still there. The bill would also prohibit transfer of any prisoners from Guantanamo to Yemen for two years.

The prison at the U.S. naval base in Cuba was opened in January 2002 to house suspected militants. President Barack Obama has pledged to close it but he already faces obstacles posed by Congress, not least of which is a ban on transfer of prisoners to the U.S. mainland.

The Obama administration moved 28 prisoners out of Guantanamo Bay in 2014, the largest number since 2009, and further transfers are expected in coming weeks. But Congress is making it hard, the White House said on Tuesday.

"It will be very, very difficult for us to achieve that goal (closing the prison) before the president leaves office as long as Congress continues to block that path," White House spokesman Josh Earnest said.