The draft Cohabitation Act will be discussed when Parliament reconvenes in the autumn after surviving a bid to defeat it in the first reading.
In an vote at the end of an all-night sitting of Parliament, IRL's motion to kill the bill garnered 32 votes, but 45 MPs voted against the motion.
That means the draft law goes into the second reading in the fall.
National conservative MPs opposed the bill even though, as supporter and Reform Party member Valdo Randpere noted, it stops short of giving same-sex couples the right to marriage or adoption.
Randpere delivered emotional remarks to MPs: "I have been a true Soviet type person myself, afraid of everything new and strange. I have been a racist, homophobic and intolerant. My transformation started when I fled to Sweden in 1982 and experienced for myself how friendly and helpful a society can be toward concerns that are actually not theirs. I stand here ready to commit political suicide to make Estonian society a little more friendly, tolerant and open," he said to applause from the chamber.
He faced numerous questions before the vote, with the Center Party's Tarmo Tamm inquiring as to how much foreign pressure there was on MPs, given that five embassies issued a joint declaration after the bill was introduced. Randpere said there was one.
The bill was initiated by 40 MPs in April; the Cabinet approved it in May.