The Senate House in the US state of Colorado is preparing for what could be its final vote on a measure to introduce civil unions for same-sex couples.

In what would be the third time the Senate approved the legislation, a final vote was planned for Monday.

The bill is expected to pass because the Senate House is now under Democratic control, and is likely to send the legislation to the Governor’s desk to be signed off.

Democratic Governor, John Hickenlooper, has also said that he plans to sign civil unions into law

In late January, a bill to legalise civil unions in the US state of Colorado passed its first vote.

The Senate committtee passed the bill three votes to two, with Democrats voting for the bill, and Republicans voting against.

This is the third year in a row a bill to allow civil unions has faced the state house. Democrats had tried to pass civil union legislation in the past two years, but House Republicans had defeated the measure.

Nine US states have already decided to legalise full same-sex marriage, most recetly, Maine and Maryland in November of 2012. Illinois has plans to vote on the topic later this year. Civil partnerships are available in several other US states.

In 2011, the governor of the US state of Delaware signed a civil unions bill into law.

Yesterday, the US state of Rhode Island was one step closer to legalising equal marriage, after its House Judiciary Committee unanimously approved a bill which would make it legal.

Last week three hundred people, both for and against equal marriage, signed up to speak at hearings at Rhode Island’s State House and hundreds more gathered outside to protest against proceedings.

Equal marriage is currently illegal according to the Colorado state constitution, however civil unions could soon be legal.