Roy Moore, who defeated Senator Luther Strange in Tuesday’s Alabama primary, is a nutcase. He has equated homosexuality with bestiality, and declared that it should be illegal. He told Vox’s Jeff Stein that there are communities in Illinois living under “sharia law.” He said that 9/11 was divine retribution for removing Christianity from public life, and refused to obey a federal order to remove a 5,280-pound granite block inscribed with the Ten Commandments that he had installed outside Alabama’s judicial building. He has said that Muslims shouldn’t be allowed to serve in Congress and that Islam is a “fake religion.” He was suspended from Alabama’s Supreme Court for refusing to recognize gay marriage, even after bans on gay marriage had been overturned by the U.S. Supreme Court.

And come December, he will almost certainly be Alabama’s next United States senator.

But that doesn’t mean that Democrats should throw in the towel and leave his Democratic opponent, Doug Jones, in the lurch. Jones is a career prosecutor who won murder convictions against the KKK members who bombed a Birmingham church in 1963, killing four black girls. He is new to electoral politics, has only raised $300,000 so far, and is competing in a deeply conservative state that Donald Trump won by 28 points—but he has the advantage of not having said things like “9/11 was divine retribution.” That Alabama Republicans have been undercut by a string of scandals only makes Jones’s sane, good government approach more appealing.

There are moral reasons for mounting a robust opposition to Moore, whose viewpoints are alarming and have no place in the Senate. An appalling hybrid of Donald Trump and Mike Pence, Moore’s theocratic leanings should terrify anyone concerned about a Republican Party that is only becoming more extreme. There’s a reason why Republican Senator Richard Shelby compared Moore to George Wallace.

But there are also very good political reasons to invest in the race. While they rally to his side after his primary victory, Republicans would prefer if Moore didn’t exist. Investing in Alabama will force them to play defense on what would normally be safe territory, in large part because Moore’s seat is so important: With a slim Senate majority and a sick John McCain, every vote counts. Ideally for Republicans, Moore will walk to victory without much fuss. Under no circumstance should Democrats let this happen. Instead, they should do everything they can to force the Republican establishment to defend Moore, while raising the temperature of the race itself. Every time Moore talks, he gets himself in trouble. Democrats should do everything in their power to make sure Republicans get in trouble, too.