On Friday, Ted Cruz denied a National Enquirer story alleging that he had participated in at least five extramarital affairs. (I am not going to link the story here. If you want to find it -- trust me, you can.)

"This National Enquirer story is garbage," Cruz said after an event in Wisconsin. "It is a tabloid smear." He went on to blame Donald Trump for planting the story in the Enquirer. (Trump and the Enquirer's CEO are close and longtime friends.) Cruz also posted a response on his Facebook page.

The denial of an affair allegation published in the National Enquirer is, in many ways, the most fitting possible end to this week in the Republican race.

This was a week in which a pro-Cruz anti-Trump super PAC published a picture of a near-nude Melania Trump in hopes of turning Utah voters off to the real estate mogul in advance of that state's primary. Trump -- Donald, not Melania -- responded, of course, via Twitter with an insinuation that Heidi Cruz, Ted's wife, had a secret that he would let out.

Heidi Cruz was forced to respond, saying she didn't have a secret.  Then Trump retweeted an image featuring a less-than-flattering picture of Heidi Cruz next to a glamorous one of Melania Trump; the image bore this caption: "No need to 'spill the beans.' The images are worth a thousand words."

Just in case you might have forgotten, this is not a race for junior high school class representative. One of these two men has a very high chance of being the Republican nominee for president. A very high chance.

While the reaction Friday morning to the Cruz allegations tended toward surprise and disgust, neither feeling really makes much sense when you consider the context of the broader campaign.

Trump has proved time and again that there are no limits to what he will say, allege or hint at when it comes to his political opponents and their families. Remember that Trump retweeted (and then deleted) a tweet that read "#JebBush has to like the Mexican Illegals because of his wife." Trump subsequently said he didn't regret the tweet and refused to apologize to Bush or his wife for it.

Trump attacked Marco Rubio as sweaty.  He went after Bush as "low energy." He has repeatedly called Cruz a liar. He has talked about the size of his hands and, by association, his genitals.  And those are just the ones I can remember off the top of my head.

Trump is going to do Trump. The problem comes when other candidates -- or their aligned groups -- conclude that the best way to slow or stop Trump is to try to out-Trump him.

Rubio spent several days earlier this month in the gutter with Trump, slamming his looks, his bathroom habits and, yes, his hand size.  It totally backfired.  People expected it from Trump. Coming from Rubio, it felt vulgar and off.  He was out of the race within days.

Then the Cruz-aligned anti-Trump group went there with the almost-naked picture of Melania, starting off another cycle of lowest-common-denominator politics that winds up splashing mud everywhere.

This is the campaign that Trump wants. Chaos. Unpredictability. Un-seriousness.

In a week in which 31 people were killed and hundreds more wounded in (another) major terrorist attack in Europe, the Republican race was about "spill the beans," nude-ish photos and alleged affairs first published in a gossip rag. Ask yourself which of the remaining three candidates in the race will prosper -- or, at least, not be damaged -- by that prurient focus. The answer is obvious.

This week -- and today in particular -- highlight what this campaign has become. An absurd race to the bottom in which the debate is over who is losing less badly and where winners are impossible to find. We -- and the GOP field -- know exactly how we got here. I'm just not sure anyone knows how we can escape it.