King County, with a population of well over 2 million, contains about 30 percent of the state’s residents. So when it comes to having political clout, that county is indeed the king.

Given that, the proposal being considered in King County to pay for stamps for voters to mail in their ballots could add to the county’s influence on Election Day.

The Seattle Times reported prepaid postage for the mail-in ballots could happen as soon as the Aug. 7 primary if the King County Metropolitan Council approves a supplemental budget request to fund the change. No other county pays for postage.

Since counties do have control over elections, this move is likely legal. Yet, it feels wrong.

As a matter of fairness, it seems either all voters in the state can return their ballots postage free, or none should have that advantage.

King County has been testing the prepaid postage for ballots in special elections, and election officials have concluded it’s a success.

Julie Wise, King County elections director, said the first tests were with three special elections in Maple Valley, Shoreline and Vashon Island. The Times reports she wanted to see how it worked with the Post Office, and if it increased voter turnout. Shoreline saw a 10 percent increase in voter turnout from its previous special election, Maple Valley went from 31 percent to 37 percent and Vashon Island from 46 percent to 52 percent.

“I’m really excited with what we saw with the Post Office, but also with voter response,” Wise said.

Secretary of State Kim Wyman, who oversees elections, supports the idea but prefers to see the entire state implement prepaid postage at the same time, so all voters are given the same opportunity, said Erich Ebel, communications director for her office. Wyman also wants the Legislature to foot the bill for all 39 counties.

Under the King County proposal, postage would cost 50 cents for each ballot, but only for those returned. So, if this model were used at the state level, it would cost taxpayers around $1.6 million, based on the 2016 presidential election in which 3.2 million Washingtonians cast ballots.

Of course, some folks would still return ballots to drop boxes, so that would likely save a few hundred thousand dollars.

Perhaps the $1 million-plus cost is worth it to boost voting a few percentage points. In addition, many voters would save the price of a 50-cent stamp. It could be considered a rebate for taxpayers for being good citizens.

The bottom line is that providing prepaid postage is a concept worth considering statewide.

But it should be an all-or-nothing proposition. Lawmakers should either approve paying postage for the entire state, or they should take action to keep King County from going out on its own.

The playing field — especially for elections — must be a level one.

Editorials are the opinion of the Union-Bulletin's Editorial Board. The board is composed of Brian Hunt, Rick Eskil, James Blethen and Alasdair Stewart