Kevin McCarthy's Capacity to Whip the Votes in His Own Party

I think what's the incentive for the Republican Party to actually have a default on this? Isn't it more in their interest to keep the pressure maximal on the White House by just continuing to kick the can down the road with various extensions so that there isn't a default and they maintain that leverage? I don't know, it's just sort of my not a political guy thinking about it. All I know is that US one year CDS are pricing in basically a 4% probability of default, which is the highest basically ever in history.