OLYMPIA, Wash. (AP) - The last mail-in ballots to be counted in Washington should decide whether a class size initiative passes.

They'll also determine the extent of Republican gains in both the state Senate and House.

Ballots counted last week showed Initiative 1351 leading by 18,000 votes - 50.5 percent to 49.5 percent.

Supporters are claiming victory for the measure that would set lower class sizes at every grade level.

Critics say it's too expensive and will cost the state about $2 billion a year to pay for thousands more teachers and other school staff.

Counties certify election results by Nov. 25th.