Trump is speaking at an event in Lawrenceville, N.J.
Just 29 percent in the state approve of Christie's performance.
Garden State Republicans say Trump should avoid making their governor his running mate.
Sean Cullen, 31, died on March 7 when he was accidentally struck by a passing motorist.
He seems headed toward a disappointing sixth place finish in New Hampshire.
"I want to make sure the people of my state feel safe and secure," he said.
Trump said the home state of his 2016 rival is "deeply troubled."
Two energy firms spent $1.8 million to buy 344,000 acres of wind power leases.
Christie says White House run is dedicated to justice for everyday Americans.
Trump edges out Carson by 1 percentage point in the Keystone State.
Each has 18 percent support from Republicans in the Keystone State.
The action will go down whether it is legal or not.
Both candidates lead Donald Trump in head-to-head match-ups.
A person close to Trump reportedly called the event a "favor" to Christie.
Workers at an Atlantic City hotel previously owned by Donald Trump endorsed Sanders.
"We’re fed up with his long neglect of the state to pursue his own selfish agenda."
The cause of the initial boom wasn't immediately clear.
“Our pension was never raided to pay for the current obligations," he said.
GOP frontrunner Donald Trump is the leader in three new statewide polls in New Hampshire, Florida...
“We’ve never had a reality TV star run for president before,” Christie said.
Christie is supported by just 5 percent of New Jersey Republican voters.
"Maybe he should do all of us a favor [and] start building his library now."
His name became a cultural brand, worldwide, beyond the sports world.
“The worst part about this is her arrogance,” Christie said.