Mr. Christie emerged as a national politician because his constituents saw him as a leader who put New Jersey first. His state battered by Hurricane Sandy and his party riven by the Tea Party, he sought needed federal assistance, and if that meant embracing a Democratic president, so what. “So what?” was a positive Christie characteristic back then. One could disagree with his methods, but he managed to make his efforts on behalf of his state seem sincere.

It must have been rough for those who re-elected him to see him hold forth Wednesday in a debate that centered on the national economy, when he’s been a net failure on the New Jersey economy. On his watch, one of the per-capita richest states in the nation has become one of its biggest laggards in economic growth, its budget woes prompting an appalling series of credit downgrades. Mr. Christie’s promises, from fixing the state’s pensions shortfall to its infrastructure, have come to less than nothing. More galling still is that he was not the only such politician on the dais. Since when does shortchanging your home state — looking at you, Ted Cruz, Marco Rubio, Bobby Jindal — qualify a public servant to be president?

It has been four months since Mr. Christie, both eyes blackened by Bridgegate, jumped into the presidential ring. After months spent in Iowa and New Hampshire, he’s in 11th place, his support among likely Republican primary voters hovering between nobody and 4 percent. His most recent quarterly contributions totaled $4.2 million, compared with $20.1 million for Ben Carson and $13.4 million for Jeb Bush. Half of Christie’s vaunted “leadership team” of New Jersey politicos didn’t give him a dime.

While Mr. Christie talks tough to empty rooms in Des Moines, Trenton is running on autopilot. Take Mr. Christie’s breakout moment, his response to Hurricane Sandy. Today, one-third of New Jersey residents hardest-hit by the storm say they are “very dissatisfied” with the state’s response so far; two-thirds say they feel “forgotten.” His fellow Republicans in the Legislature are embattled, thanks in part to the example he’s set. Mr. Christie earns $175,000 a year, the fifth-highest-paid governor in the nation, according to the Council of State Governments. Yet he hasn’t offered to forgo his salary or take a pay cut, as nearly a dozen full-time governors have done. Florida’s Sun Sentinel demanded Tuesday that Mr. Rubio, who earns a nearly identical salary and has missed 99 votes while on the campaign trail, more than any other United States senator this year, simply resign.