There will be two big stars at the Republican National Convention, and neither of them will be Mitt Romney. One will, of course, be Paul Ryan, Mr. Romney’s running mate. The other will be Chris Christie, the governor of New Jersey, who will give the keynote address. And while the two men could hardly look or sound more different, they are brothers under the skin.

How so? Both have carefully cultivated public images as tough, fiscally responsible guys willing to make hard choices. And both public images are completely false.

I’ve written a lot lately deconstructing the Ryan myth, so let me turn today to Mr. Christie.

When Mr. Christie took office in January 2010, New Jersey — like many other states — was in dire fiscal straits thanks to the effects of a depressed economy. Unlike the federal government, states are required by their constitutions to run more or less balanced budgets every year (although there is room for accounting gimmicks), so like other governors, Mr. Christie was forced to engage in belt-tightening.

So far so normal: while Mr. Christie has made a lot of noise about his tough budget choices, other governors have done much the same. Nor has he eschewed budget gimmicks: like earlier New Jersey governors, Mr. Christie has closed budget gaps in part by deferring required contributions to state pension funds, which is in effect a form of borrowing against the future, and he has also sought to paper over budget gaps by diverting money from places like the Transportation Trust Fund.