At issue this week: the budget. The setting: the Senate floor. Cruz, along with Republican Sens. Rand Paul of Kentucky, Marco Rubio of Florida, and Mike Lee of Utah called for Senate Republicans to block efforts to move the budget debate to a conference committee (both the House and Senate have separately passed budgets) without a guarantee Democrats won't surreptitiously try to insert an automatic increase to the nation's debt limit through a procedural tactic.
"We could go to conference right now, today, if the Democrats would simply say, we won't raise the debt ceiling with just using 50 votes," Cruz said on the Senate floor Thursday.
McCain, along with moderate Sen. Susan Collins (R-Maine) and others, have challenged their conservative colleagues, decrying the effort to delay, especially after Senate Democrats finally passed a budget for the first time in three years. The obstruction, McCain said Thursday, threatens to "paralyze the process."
"How do we reconcile legislation that's been passed by one body and the other body? That's what we've been doing for a couple hundred years. Perhaps the senator from Utah doesn't know about that," McCain said in a dig against Lee, a tea party-backed senator who unseated incumbent Republican Robert Bennett in 2010.
In an effort to assuage concerns -- or perhaps highlight his belief that they are unfounded -- McCain pointed to the fact that the House GOP majority will also be a part of the conference process, protecting against the outcome feared by the conservative senators.
But none of it would sway Cruz, who has quickly established himself as the fiery voice of the right in the Senate.
"I will suggest to my friend from Arizona, there may be more wacko birds in the Senate than is suspected," the Texas senator said Thursday, before wagering McCain could not secure the willingness of most Senate Republicans to allow the risk of Democrats raising the debt ceiling.
So confident was Cruz that he offered to wear an Arizona Diamondbacks hat at a Houston Astros home baseball game if he was proven incorrect.
The House GOP has been riven by discord since the 2010 wave election ushered in a new class of lawmakers with little regard for the "way things work" or loyalty to party leadership. In the more orderly Senate, we are starting to see something similar take place. It's grown clear that the disputes between McCain and Cruz are not limited to a single issue. Budget fight? Check. Foreign policy spat? Done.
Cruz's "wacko birds" remark was a reference to a pejorative label McCain gave him, Paul and Rep. Justin Amash (R-Mich.) earlier this year. McCain and his close ally, Sen. Lindsey Graham (R-S.C.), objected strongly to Paul's marathon filibuster over the Obama administration's use of unmanned aerial drones. Joining Paul were Cruz, other conservatives, and notably, Senate Minority Leader Mitch McConnell (R-Ky.), who has been mindful of his image on the right as he seeks to avoid a primary threat in 2014.
With the departure of Jim DeMint, who for years was GOP antagonist No. 1 in the upper chamber, there was a gap on the political right of the Senate at the beginning of the 113th Congress. Cruz, with his staunch conservatism and outspoken style, is filling that space with his blistering criticism of Democrats, and as this week showed, Republicans too.
With the rise of Paul, Cruz, and to a lesser extent Lee, the effect of conservative Senate victories (all three defeated more moderate Republicans in contested intraparty fights) in recent years is becoming more and more obvious. McCain, given his seniority and political style, isn't one to back down from a fight. Neither is Cruz.
And while that means more fireworks on the Senate floor, it could also slow a legislative process that has already been panned for moving at a snail's pace during the past several years.