Republicans have a good chance to win control of the Senate this November. Democrats are on the defensive over Obamacare, the president is unpopular, and history suggests second-term mid-terms are nearly always unlucky for the White House.

Given that, why is there so much division, backbiting, and bad blood among some Senate Republicans? Last seen during the government shutdown fiasco, the GOP malady returned this week with a debt ceiling mini-fiasco, and it threatens to revisit the Senate any number of times before Election Day.

There is at least one common thread in the shutdown and debt ceiling incidents, and that is Sen. Ted Cruz. For whatever reason, the Texas freshman has at times goaded his party to dysfunction, embarrassment, and defeat. (Not quite singlehandedly; others, like Sens. Mike Lee and Rand Paul, have also been done their bit.)

Many in the GOP believe Cruz is just out for himself. But even if that's true, they have to remember that he represents more than just Ted Cruz. There are a lot of Republicans -- it's not clear how many, but a significant portion of the party's base -- that cheers Cruz on when he battles with Senate Majority Leader Mitch McConnell. They want to see a Republican throw a wrench in the Washington spending machine, even if it creates chaos and damages the GOP's standing with independent voters. And it is that conviction that is really behind the party's problems; it is why Republicans would not enjoy smooth sailing even if Cruz were to retire tomorrow.

What was remarkable about the brief debt limit fight is how small the stakes were. Republicans, burned by recent failures, did not propose to add some huge fiscal reform -- a restructuring of entitlements, for example -- to a measure to raise the debt limit. Instead, they discussed more modest measures, like reworking the cost-of-living adjustment for veterans that was part of the recent bipartisan budget deal.

When the week began, Senate Republicans expected the House to attach something small to the debt limit bill that would be sent to the Senate. They were taken off guard Tuesday morning when House Speaker John Boehner announced that wouldn't happen -- that the House, relying on mostly Democratic votes, would instead pass a bill to raise the debt limit with no strings attached.

Senate Republicans met in their weekly lunch a few hours after Boehner's announcement. The short version of events is that McConnell urged colleagues to allow a vote on the House debt limit bill. If the GOP did not object, it could be passed with a simple 51-vote majority, and since there are 55 Democrats in the Senate who would vote for it, every Republican could vote against it and it would still pass. Problem solved; there would be no more default talk, and Republicans could go back to slamming Democrats over Obamacare.

Then Cruz stood up and said there was no way in the world he would stand by and allow a debt ceiling increase to be passed with just 51 votes. Cruz insisted on a 60-vote threshold, which the rules allowed him to do. That meant at least five Republicans would have to join Democrats for the debt limit to be raised.

It would be an understatement to say that many of Cruz's GOP colleagues were righteously ticked off at him. Nobody wanted to vote to raise the debt limit, but many believed strongly that a losing fight over spending would damage the party. Besides, Cruz didn't even have a plan for what to do had his Republican colleagues improbably decided to go along with him.

So after some testy exchanges at the lunch, and a lot of negotiating in the afternoon, McConnell and other leaders decided to vote for the debt limit increase. Then several other Republicans, mostly those in unthreatened seats, agreed to vote along with them to provide cover. The bill passed with 12 Republicans joining all 55 Democrats.

Cruz, of course, voted no and accused lawmakers who voted yes of "not listening to the American people." He even suggested those who are up for re-election — a group that very prominently includes McConnell himself — might soon pay a heavy price. "Sometimes, come November, the people remember," Cruz said.

In the end, the gambit accomplished nothing for Senate Republicans. Some GOP lawmakers who already disliked Cruz now dislike him even more. But the episode did remind the Republican leadership, as if it needs any reminding, that there are conservatives around the country who are deeply frustrated by the GOP and want it to show some fight.

To them, Cruz represents that fight. Maybe they've been misled. Maybe they're living in a fantasy land. But that's what they believe. Republican leaders have to keep them in mind as November approaches.