Make sure you read rules 200.2 and 200.3. There are no longer turns, and any player may make a proposition as often as he would like!
I'd also like to make reference to rule 200.8: Each player always has exactly one vote, and must record their vote both on the thread poll and on the thread itself (for ease of calculation and scoring). These votes must match. In the case that they don't, the written vote will be the one counted.