You might not know it, but Missouri is one of the most important states in the union this election cycle. Republicans are on the cusp of seizing control of every branch of the government; the Supreme Court enjoys a conservative majority, a projected $1.8 billion Romney campaign has tied the Democratic incumbent in recent polls in a struggling economy, the House is theirs to keep, and if Republicans can pick up four seats in the Senate, even assuming a Democratic victory for the presidency, they will become the majority. Their ability to do this depends almost entirely on the fate of one Claire McCaskill (D-MO), who is one of the 21 Senate Democrats up for reelection this year, and whose seat is in terrible jeopardy of being lost. This cannot be allowed to happen, and it is imperative that we do everything in our power to make sure it does not.

Ms. McCaskill is a freshman Senator. She was elected in the 2006 landslide election, popularly known as the Bush referendum, in a state that voted for Bush twice and for McCain in 2008. Her position was never a safe one, and in 2010, she voted with her party to pass the Patient Protection and Affordable Care Act, or Obamacare. That was all but political suicide. 70% of Missourians opposed it, and her Republican counterparts incessantly remind Missouri that Claire “cast the deciding vote” to pass it.

And until very recently, it looked like the end of Ms. McCaskill’s senatorial career was in sight. Former Representative Todd Akin (R-MO) was 11 points ahead in the polls, and millions of dollars were flooding into Missouri to support him. Fortunately for the Democrats, when asked about abortion in the case of rape, Mr. Akin made the claim that “if it’s a legitimate rape, the female body has ways to try to shut that whole [pregnancy] thing down.”

That remark ignited a national firestorm. Republican leaders, from Mitt Romney to Senate Minority Leader Mitch McConnell (R-KY) have publicly called for him to step down. The National Republican Senatorial Committee has said it will halt spending on his campaign, and the conservative Super PAC Republican Crossroads, brainchild of one Karl Rove, has said that no money will enter Missouri as long as Todd Akin is the Republican candidate for the Senate. In a July 30 poll, a week before Mr. Akin won the Republican primary, a Rasmussen poll had him beating Ms. McCaskill 47 percent to 44 percent. Now, McCaskill is leading 48 to 38. The tables have turned.

It is a time for celebration, but the elections are still a political century away. And Republicans can put as much pressure as they want on Todd Akin, but if he does drop out, his career on the hill is probably at an end, and he seems to be banking on the idea that, when push comes to shove, Republicans will want to win the Senate more than they will want to keep him out of it. Further, Mr. Akin recently visited Tampa for a meeting with the Council for National Policy, a group that, among other things, brings wealthy donors together to strategize and meet with conservative politicians. He might be down, but he is far from out.

It is imperative, then, that we make sure Claire McCaskill stays ahead in the polls. If Republicans do not win in Missouri, it will be incredibly difficult, perhaps insurmountably so, for them to become the majority in the Senate. The McCaskill campaign, just like every other, would benefit greatly from intelligent, informed, dedicated volunteers, just the sort of people Wash. U. is likely to have in abundance. No time to commit? Then change your voter registration. Whatever your home state, it is likely of far less importance in this election than is Missouri, and you’ll be doing the world a favor by casting a Democratic ballot this year. It is a very real possibility that Republicans will snatch the presidency from Obama in November, and if so, Claire McCaskill might be all that stands in the way of a completely red government.