Gay and lesbian couples in Oregon are making plans to marry in the event a federal judge on Monday strikes down the state's ban on gay marriage.

U.S. District Judge Michael McShane announced Friday he intends to file his ruling on Monday at noon.

All parties present during an April 23 hearing, including the state, called on McShane to strike down Oregon's 2004 voter-approved constitutional amendment limiting marriage to heterosexual couples.

“We simply can't imagine a rationalization for the ban,” a lawyer for the state told McShane.

In anticipation of the ruling, Oregon United for Marriage has announced plans for wedding venues in Portland and Eugene, where it will provide officiants, photographers and flowers.

While Oregon has a three-day waiting period, many counties will, for a fee, waive the requirement for a “good cause.”

If McShane strikes down the ban on Monday, Oregon will become the 18th state – plus the District of Columbia – to allow gay couples to marry. An appeal in the decision is not expected to be filed since no defendant in the case supports the ban.

In the meantime, the National Organization for Marriage (NOM) has appealed a ruling rejecting its request to intervene in the case.

(Related: Federal judge denies NOM's request to intervene in Oregon gay marriage case.)