For the second campaign cycle in a row, Washington State voters may head into an election year not knowing how their voting system is going to work.

Last month the U.S. District Court in Seattle struck down the voter-enacted “top-two” system that became law after last year’s election.

The Washington state Democratic, Republican and Libertarian parties had filed motions urging the court to throw out the new system before it even goes into use.

Judge Thomas Zilly’s declaration that the top-two system — in which the two biggest votegetters in a primary, regardless of party affiliation, move on to the general election — violates political parties’ First Amendment rights of free association signals that the new system could go the way of the one it replaced.

For almost 70 years, Washington voters cherished their “blanket” primary system in which they were able to pull the lever for Democrats and Republicans on the same ballot.

In 2003, the courts sided with the parties in ruling that the system was unconstitutional. The parties had argued that only party members should have the right to decide who will represent them on the ballot. The 9th U.S. Circuit Court of Appeals agreed, junking the blanket primary, and the U.S. Supreme Court declined to review the decision.

The state parties, the Legislature, the governor, the secretary of state and the voters argued over how best to replace it last year. Finally, they settled on a “Montana-style” system in which voters can pick either a Republican or Democratic primary ballot on or before election day, and then choose candidates for all offices only from one party’s offerings.

The parties accepted the Montana system, but on the same day last November that voters used it for the first time, they also rejected it for future elections by approving a ballot initiative to institute the top-two system.

“It’s always been obvious that the top-two primary was unconstitutional,” state Republican Party Chairman Chris Vance said in a statement. “Now it’s time for the state of Washington to sit down with the political parties and arrive at an agreement on a primary system that is constitutional and that we can all live with.”

Vance and his Democratic counterpart Paul Berendt want more control over deciding which candidates can use their party label. (Berendt did not return phone calls for this report.)

Last year, when it seemed that the Legislature might not act in time for the September primary, all major parties vowed to forgo the primary in favor of nominating conventions or caucuses.

If Zilly’s decision stands, the state would automatically revert to the Montana system used last year. But the Legislature could change the law again and if the parties weren’t satisfied with the result, they could still opt to have caucuses or nominating conventions instead.

King County Republicans and Democrats already convened conventions in June to choose the party’s official nominees for September’s local elections.

Vance has asked all Republican participants to abide by the decisions made at the local party convention in Bellevue.

In what might be a sign of things to come, however, one loser said he would shun the decision. A candidate for the King County Council told the Seattle Times he would not abandon his campaign and that he would file for office, though maybe not as a Republican.

Washington Secretary of State Sam Reed told the paper that election officials would not heed the conventions’ outcomes and that anyone who files can run under the party label of his or her choosing. (Reed did not return phone calls for this report.)

Republican Party officials, however, threatened to sue if anyone not endorsed tries to run under the GOP banner.

Whether such a problem would ever arise at the federal level is unclear, but the Republican National Committee for one has a procedure in place.

The RNC’s rules state that in the event two “nominees” are offered, the one chosen by the party will be viewed as the nominee for federal elections, Vance has said.

David Moon, program director for the nonpartisan electoral reform group FairVote-The Center for Voting and Democracy, suggested that both sides in Washington state are partly right and partly wrong.

On the one hand, Moon said, the parties have valid concerns about top-two voting being slanted if one party runs just one candidate and the other party has a fractured slate. On the other hand, he added, “I don’t think that the parties’ free association concerns should trump greater voter choice.”

FairVote is preparing to file an amicus, or friend-of-the-court, brief with the federal appeals court that urges adoption of another system entirely — one which might ameliorate both sides’ concerns. Under one such system, known as instant-runoff voting, voters rank their choices, with the lowest finishers eliminated one by one and their votes reassigned to second-choice candidates until the top finisher exceeds 50 percent of ballots cast.

One issue that remains unclear is the effect that Zilly’s decision could have on Louisiana, whose system, despite some differences, has long pitted the top two finishers in an all-party contest against each other, regardless of party.

Moon suggests that Louisiana is on slightly safer legal ground, because under its system, a candidate who wins 50 percent in the all-party first round wins the election. A runoff election is held only if the top finisher wins less than 50 percent.

That design, he said, makes Louisiana’s all-party round somewhat less like a primary and more like a general election, which could make it harder for the parties to argue that their right to choose their nominees is being hurt.

However, the court’s ruling in the Washington case “was pretty sweeping in protecting parties’ free-association rights, and I think there could be a lot of potential fallout,” Moon said. “A lot of states could face problems if they don’t grant parties enough leeway to control who runs with their party label.”