Last week's presidential debate (major candidate division) illustrated three very real obstacles the Republicans face in 2016. The most prominent obstacle, of course, remains Donald Trump. His refusal to disavow a three-way race in November—and the gentle treatment he received from his opponents—demonstrates that the view he is a sideshow who will fade away as things get serious is merely wishful thinking. His popularity among a large segment of Republican primary voters inhibits his rivals' ability to appeal to the general electorate—a factor underscored when Marco Rubio refused to criticize his attack on Megyn Kelly.

The second GOP obstacle on display was how two candidates from the party's non-extreme wing, Rubio and Scott Walker, undercut the party's effort to frame the abortion issue in a less divisive way. They reprised the extremism that already cost Republicans Senate seats in Missouri, Indiana and possibly elsewhere in 2012. It's a challenge only further exacerbated by Jeb Bush's promise to rekindle the related controversy he initiated when he tried to overrule the decision of Terry Schiavo's husband to withdraw her feeding tube, after she had been brain-dead for years, and in compliance with her previously expressed wishes.

Neither of those obstacles, though, represented a surprise. Both have a common root in the very angry, deeply conservative Republican primary electorate. The displays on Thursday merely showed how much harder it will be to manage the course of a tough intra-party campaign than it is to draft dry memos by Republican strategists focused on winning in November.

The third troublesome issue for the GOP to arise in the debate, though, was unexpected; it was presented by John Kasich, the dark horse candidate of those hoping to avoid going to the general electorate with a nominee and platform burdened by a commitment to right-wing purity.

Kasich's favorite way to distinguish himself from his competitors was an implicit but sharp contrast between the administrations of Bill Clinton and George W. Bush, with Clinton coming out way ahead—and on an issue that the Republicans claim as one of their strongest: reducing the federal deficit.

While the first two have been discussed, the heretofore unheralded success of the Kasich-Clinton collaboration on balancing the budget deserves attention both for its novelty and its potential to further complicate the Republican attack on Hillary Clinton. Kasich has drawn a double-edged sword. To the extent that he gains in the intra-party contest by trumpeting the undeniable fact that the only time the budget has been balanced in decades was during his Budget Committee chairmanship in 1998-2001, he reminds voters that it was only during Clinton's presidency—and not under Reagan or either Bush—that this cherished Republican goal was achieved. It's a narrative that undercuts one of the GOP's favorite critiques of the Democrats.

True, Bill was the president who was Kasich's indispensable partner, not Hillary. But blaming her for what they describe as the excesses of that time, while denying that she deserves any credit for what they hail as a major accomplishment, will not be easily done. Further adding to their dilemma is that two of the most important elements that led to the Kasich-Clinton balanced budget were increased taxes on the wealthy and constraints on military spending. Not only did the Republicans oppose that approach then—and continue to oppose them now—but it was the reversal of both policies by George W. Bush and a Republican Congress that put the budget back into deficit.

At this point, a disclaimer is necessary: I voted against the Kasich-Clinton deal, in substantial part because it called for future reductions in Medicare reimbursements, reductions that were never implemented and were recently repealed. But I am not the likely Democratic candidate—Hillary is. (If I believed that someone with my views on the appropriate levels of taxation, and domestic and military spending could win the presidency, I would be running myself.)

The case for the Democratic fiscal responsibility is indisputable. The fiscal decisions taken by the first Clinton administration created the context that made possible the bipartisan compromise that Kasich cites as one of his major qualifications for the presidency. And, of course, the reason Kasich has no Republican rivals for the budget-balancer title is because the Republicans abandoned that approach after they came to power in 2001.

Ordinarily, the record of the current Democratic administration would play a larger role in the next election than the previous one, and surely Clinton's role as President Obama's secretary of state will be prominent in the campaign. But spouses of a previous president are not ordinarily candidates. Much of the Republican assault on Hillary Clinton draws on her role in the '90s and the allusion to "scandals" from that time—allusions notwithstanding the fact that Kenneth Starr told the House Judiciary Committee in 1998 that after spending millions of dollars over several years, he had no basis for any negative conclusions about Hillary regarding Whitewater, FBI Filegate, the White House travel office, Vince Foster or anything else.

Substantively, the Republicans will attack Hillary as a Democrat who wants to spend too much on domestic programs and too little on the military, all while keeping taxes too high. John Kasich's reminder that this mix in the Clinton administration made possible a rare balanced budget is not as explicit a defense for her as Kenneth Starr's, but it will at the least make demonizing her as wildly fiscally irresponsible problematic.

This will be especially true if she runs against Jeb Bush. In the inevitable contrast that this race will feature between the administrations of their husband and brother respectively, expect to hear a lot about who balanced the budget and how.

This also means that in the unlikely event that we have a Clinton-Kasich contest, it will be interesting to see how Kasich trumpets one of his proudest accomplishments without sharing credit for it with the administration with which his opponent is so closely identified—and while calling for the lower tax rates and much higher military spending which will make it highly unlikely that it will soon be repeated.

Barney Frank is a Politico columnist and a former Democratic representative from Massachusetts.