His neutrality on the tax compromise suggested that he would not be an automatic vote for Mr. DeMint, whose political fund contributed to his campaign. Neutrality also lets him avoid having to pick sides, for now, between Mr. DeMint and Mr. McConnell.

“I think there’s a real chance we’ll be reasonably united,” he said of Senate Republicans. “If we are, then I don’t have to pick a camp.”

Whether Mr. Toomey’s moderating statements are mere posturing may become clear soon enough. Even he acknowledged that sooner or later he would be caught up in the politics of Capitol Hill. He said he expected that his alliances would periodically shift, depending on the issue and the context. Political analysts agreed…

Mr. Toomey kept social issues on the back burner, saying then as he does now that they were of lower priority than restoring the economy. During the campaign, he refrained from making statements like one earlier in his career when he said that “my idea of gun control is a steady aim,” and he did not promote his endorsement by Ms. Palin. He also said he would have voted to confirm Justice Sonia Sotomayor, Mr. Obama’s first nominee to the Supreme Court.