Australians will be asked to take part in a postal vote on same-sex marriage vote after the Senate killed off the Government's plan for a compulsory plebiscite.

The Upper House's rejection of the plan came after Labor frontbencher Penny Wong launched an emotional attack on the Government proposal and former prime minister Tony Abbott earlier urged people to "vote no" to "stop political correctness in its tracks".

Look back on all of the day's political developments in our blog.