Down-to-the-wire preparations are being made for next Wednesday’s hearing before the U.S. Supreme Court on whether to disclose the names of approximately 138,000 people who signed petitions seeking to overturn an expanded domestic partnership law for gay and lesbian couples.

Protect Marriage Washington, which advocates for traditional marriage, unsuccessfully sought to overturn that law by placing Referendum 71 on the November ballot.

It’s seeking to bar the public release of those names.

A Supreme Court decision would likely affect not just Referendum 71 but public disclosure rules for all referendum and initiative petitions in the state, and potentially, about two dozen other states with referendum and initiative procedures.

Today, state Attorney General Rob McKenna flies out to Washington, D.C., to begin final preparations -- including two mock arguments.

“There’s a lot at stake here,” McKenna said in a press conference Monday. The case “provides a direct challenge to transparency.”

The state argues that those who sign petitions are acting like quasi-legislators, in a public arena, rather than engaging in constitutionally protected political speech, which can be anonymous.

Also today, the attorney for Protect Marriage Washington announced he filed his reply brief, disagreeing with the state’s argument.

“The First Amendment allows individuals to engage in political speech without being forced to reveal their identities,” James Bopp Jr. said in a statement. “When public disclosure laws like those in Washington force people to reveal themselves, individuals cannot speak without worrying about threats to themselves, their families, or their jobs.”