As gay people around the country reveled on Sunday in the historic Senate vote to repeal “Don’t Ask, Don’t Tell,” a liberal media watchdog group said it planned to announce on Monday that it was setting up a “communications war room for gay equality” in an effort to win the movement’s next and biggest battle: for a right to same-sex marriage.

The new group, Equality Matters, grew out of Media Matters, an organization backed by wealthy liberal donors — including prominent gay philanthropists — that has staked its claim in Washington punditry with aggressive attacks on Fox News and conservative commentators like Rush Limbaugh and Glenn Beck…

For the gay rights movement, the right to marry is the holy grail, because so many other benefits — including Social Security and health benefits for gay partners, adoption rights, tax benefits and others — flow from it.