The bill received votes of support from 206 House representatives and two of the 250 senators, while half of the current joint parliament is 367 (there are by-elections pending for vacant seats).
Four senators voted against the bill while 10 representatives and 84 senators abstained. Nine representatives and 127 senators chose "no vote".
The constitution requires a constitutional bill to have the approval of at least one-third, 84, of the senate.
On March 17 night, House Speaker Chuan Leekpai ordered the parliament to go ahead with a vote on whether to pass the bill after an 11-hour debate. The move came after members of parliament and senators voted 473:127 in favour of a motion put by deputy leader of the ruling Palang Pracharath Party Paiboon Nititawan that parliament follow its agenda and vote.