I-732 sponsor Yoram Bauman (center) talks to media and supporters after he and others turned in signatures for the ballot measure.

Sponsors of an initiative to the Legislature to impose a carbon emission tax on certain fossil fuels submitted what the campaign estimated at more than 243,000 signatures Thursday at the state Elections Division office in Olympia.

Initiative 732 sponsor Yoram Bauman says his team so far has collected about 294,000 signatures and hopes to gather a total of 330,000 sigs. The initiative sponsors say they plan to turn in the remaining signatures by the Dec. 31 deadline to submit signatures for initiatives to the 2016 Legislature.

Just like initiatives to the people, initiatives to the Legislature need at least 246,372 valid signatures to be certified. Elections Division officials suggest a 25 percent buffer (about 325,000 signatures total) to cover duplicate or invalid signatures.

If I-732 sponsors turn in their planned number of signatures, the Elections Division likely will do a 3 percent sample check of those sigs. If the review shows there are enough valid signatures, Secretary of State Wyman will certify the results, sending the measure to the Legislature. There, three things can happen: 1) the Legislature enacts I-732, thus making it state law; 2) the Legislature fails to take action on it, automatically putting the measure on the 2016 General Election ballot; or 3) the Legislature approves an alternative to I-732, with both measures winding up on the 2016 fall ballot.