SAN FRANCISCO — Ever since the federal challenge to Proposition 8 was filed, Northern District Chief Judge Vaughn Walker has been leading the parties toward an early trial. On Wednesday, he didn’t loosen the leash a bit.

Walker swept aside attempts by Prop 8 supporters to knock out the case on summary judgment. His ruling, delivered from the bench, came just an hour after argument on the motion had concluded. Walker and two U.S. Supreme Court-hardened lawyers sparred on key issues expected to affect the outcome of the case, and on each of them, his ruling helps same-sex marriage advocates more than it hurts them.