Senator Richard Shelby may not change the outcome of Alabama’s special election with these words: “I couldn’t vote for Roy Moore. The state of Alabama deserves better.’’

But by speaking them, Alabama’s senior Republican senator put principle ahead of party — and that counts for something in these mean, partisan times. Still, if Moore wins, the real test will come in January, when the Senate must decide what to do about a newly elected member who enters with credible charges of child molestation lodged against him.

For the moment, Shelby made news just by breaking with precedent. “For a state’s senior senator to not support his party’s nominee for the other seat is almost unheard of,’’ noted an editorial published by the Alabama Media Group, which represents the state’s largest newspapers. The last time it happened was 1990, in Louisiana, when the Republican nominee was David Duke, a former KKK leader.

Shelby was first elected to the US Senate in 1986, as a Democrat, and reelected in 1992 — the last time Alabamians sent a Democrat to the Senate. He switched to the GOP in 1994, and Alabama voters have backed him enthusiastically ever since. Last year, he won reelection with 64 percent of the vote. Like Moore, Shelby is antiabortion, pro-gun, and favors tougher immigration rules. Michael Graham, a conservative commentator who formerly ran Republican primaries in several Southern states, doesn’t think Shelby’s anti-Moore declaration puts him at any real political risk. “He has been around a long time. If there’s any danger for a guy like him in a Republican state, then every incumbent Republican is in danger across the country from the Bannon wing of the party,’’ said Graham.

Unlike Jeff Flake, a Republican senator from Arizona, who sent a $100 check to Moore’s Democrat opponent, Shelby isn’t supporting Moore’s rival; he said he cast an early vote for “a distinguished Republican write-in.’’ Yet it still takes political courage to do even that much crossing of current Republican bomb-throwers like Steve Bannon. At a recent Alabama rally for Moore, Bannon launched an ugly attack on Mitt Romney, assailing the 2012 Republican nominee for not serving in the Vietnam War — all because Romney tweeted that a Moore victory “would be a stain on the GOP.’’ Bannon also called Flake “a total embarrassment’’ and mocked the amount of the check he wrote for Jones.

On CNN’s “State of the Union’’ Sunday show, Shelby said he has no reason to disbelieve the women who came forward to say Moore pursued them sexually when they were teenagers. “I think, so many accusations, so many cuts, so many drip, drip, drip — when it got to the 14-year-old’s story, that was enough for me. I said I can’t vote for Roy Moore.’’

If Moore wins anyway, what next? Senator Cory Gardner, Republican of Colorado and chairman of the National Republican Senatorial Committee, said Moore “will never have the support of the senatorial committee. We will never endorse him. We won’t support him.’’ Senator Tim Scott, Republican of South Carolina, said, “If he wins, we have to seat him. Then, there will immediately be an ethics investigation.’’

Shelby also said that if Moore wins, he will be seated, “and we’ll see what happens after that.’’

And he won’t be the only one watching. How vocal will Shelby be if, over his passionate objection, his fellow Alabamians choose to send Moore to Washington? Shelby has said that he’s worried that Moore’s possible election will hurt the reputation of a state that’s evolving and trying to break old stereotypes. “It’s not 1860. It’s not 1900. It’s not 1940. It’s not 1964 or 1965. It’s 2017. And Alabama in a lot of ways is on the cutting edge, on the cusp of a lot of good things,’’ Shelby told The Washington Post.

Shelby broke precedent before election day. If Moore wins, challenging him requires even more courage.

Joan Vennochi can be reached at vennochi@globe.com. Follow her on Twitter @Joan_Vennochi.