How Chris Christie could have a chance

Could Chris Christie be president?
Could Chris Christie be president?   

New Jersey Gov. Chris Christie on Tuesday becomes the 14th member of the 2016 GOP presidential field and a massive long shot to secure his party's nomination.

It wasn't supposed to be this way.

Before Bridgegate and a moribund approval rating in his home state, Christie was supposed to be among the front-runners, a straight-talking blue state governor with swagger, an abiding love for Bruce Springsteen and a ready font of Wall Street cash.

Now Christie has an approval rating of just 30 percent in New Jersey, barely registers in early state polling—where he often trails Donald Trump—and most of the Wall Street money is flowing to former Florida Gov. Jeb Bush, Florida Sen. Marco Rubio and Wisconsin Gov. Scott Walker.

The conventional wisdom holds that Christie doesn't have a prayer. And the conventional wisdom is probably right. But it's not totally, completely impossible.

Christie is a highly skilled retail politician who has can wow the kind of town hall meetings that New Hampshire victories are built on. As soon as he finishes his announcement speech at his high school in Livingston, New Jersey, Christie is racing back to New Hampshire, where his candidacy will live or die.

Read More Hillary's campaign stumbles on trade

His first task: Raise his poll numbers enough to get in the first debate on Fox News in August. If he can't do that, Christie is probably toast before the voting even starts. But he if can, Christie will be a force to reckon with on the debate stage.

Republican U.S. presidential candidate and New Jersey Governor Chris Christie arrives on stage to make the formal announcement of his campaign for the 2016 Republican presidential nomination at Livingston High School in Livingston, New Jersey, June 30, 2015.
Brendan McDermid | Reuters
Republican U.S. presidential candidate and New Jersey Governor Chris Christie arrives on stage to make the formal announcement of his campaign for the 2016 Republican presidential nomination at Livingston High School in Livingston, New Jersey, June 30, 2015.

And New Hampshire loves a come-from-behind straight-talking upstart. The problem is, Christie is vying for that title with a pile-up of GOP rivals all running in the center-right, "establishment" lane of the GOP. That group includes Bush, John Kasich, Walker and others (though Bush suffers from being the perceived front-runner, never a comfortable spot).

New Hampshire is especially important to Bush who is not expected to finish at the top in Iowa, which is friendlier to social conservatives such as Rick Santorum and Mike Huckabee. If Christie begins to catch fire in New Hampshire, expect the Jeb Bush money machine to come after him with a barrage of negative ads. There is plenty of fodder, beginning with the Bridgegate scandal, which never directly touched Christie but did implicate senior aides.

In addition to his theme of "telling it like it is"—Christie won't use a teleprompter on Tuesday—the New Jersey governor is hoping to be the wonk candidate. He has given a series of detailed—and little noticed—policy speeches in recent weeks on the economy, foreign policy and other issues.

His economic plan includes "revenue neutral" tax reform that would lower rates while eliminating deductions and credits. It's the kind of sensible approach that deficit hawks like but that does not really stir the hearts and minds of supply-side conservatives who want deep tax cuts no matter the revenue impact. Other candidates pushing easier to explain flat-tax proposals could outflank Christie on the issue.

Read MoreBush launches with an eye on Rubio

But one thing Christie's policy specifics could do is pressure Bush to move more quickly to put meat on the bones of his promise to boost U.S. economic growth to 4 percent per year. Many economists dismissed Bush's pledge – which would double the current rate of growth—as an impossible dream. But the former Florida governor is sticking with it, which means he is going to have to come up with tax and other policies that could rev up the American economy.

Everything has to go right for Christie to emerge as a serious contender for the GOP nomination. He has to get into the first debate, he has to win New Hampshire and he has to fend off attacks over his scandal-plagued past. Chances are he won't be able to do it. But with 14—and soon to be 16—candidates in the Republican race, literally anything can happen.

—Ben White is Politico's chief economic correspondent and a CNBC contributor. He also authors the daily tip sheet Politico Morning Money [politico.com/morningmoney]. Follow him on Twitter @morningmoneyben.