CLEVELAND - He gave a speech that prompted a rallying cry on the floor of the Republican National Convention, defended the GOP presidential nominee's wife against plagiarism, and blasted a U.S. senator as selfish.

As Gov. Christie capped a week in the spotlight - and as a top advocate for Donald Trump - he pledged to New Jersey Republicans that he would play a quieter role when his term as governor ends in January 2018.

"I will retreat to the role of used-to-be," the governor said at a breakfast Thursday for the state's delegation, describing his role model for departing office as former President George W. Bush: "He never got out there and decided to become a pundit or talking head," but "conducted himself with honor and dignity."

If Christie - who was urging state Republicans to step up and take his place leading the party - leaves the governorship quietly, "it might not be willingly," said Julian Zelizer, professor of history and public affairs at Princeton University. If Trump loses the November election, Christie "might benefit from some time outside the public spotlight."

He said the governor's high-profile role this week - dominated by his convention-speech turn as prosecutor, hammering presumptive Democratic presidential nominee Hillary Clinton as he repeatedly asked the crowd, "Guilty or not guilty?" - could carry political risk.

Once the "energy of the convention is over," Christie "once again will be left associated with a kind of extremist politics," Zelizer said, referring to the attention the governor received after endorsing Trump once his own presidential campaign ended.

In Cleveland, the governor's speech stirred approving chants of "Lock her up!" - a phrase that resonated throughout the week.

Christie "set the tone for why it shouldn't be Hillary Clinton," Mary Beth Dougherty, a member of the Pennsylvania delegation from Schuylkill County, said Wednesday.

Of the chant, she said, "I agreed with it," then laughed. "I was doing it."

So did a man in the audience as Christie addressed a Latino group at a luncheon Wednesday. As the governor began to speak, the man called out: "Lock her up!"

"I didn't start that part, you know," Christie said.

The crowd spontaneously took up the mantra during each of the first two speeches Wednesday night. And when it arose later, during a speech by Florida Attorney General Pam Bondi, she ad-libbed, "Lock her up - I love that."

Mark McCaig of Houston said Christie's speech "really brought home the fact that Crooked Hillary is more concerned with her personal power than the good of the American people."

But sitting nearby, fellow Texan Jonelle Fields said the chant is "not really going to help us."

"There can be anger, but channel it - don't just yell and scream and have vitriol," Fields said.

Democrats criticized the chants - and Christie's speech - Thursday. "When Chris Christie did the thing about 'Guilty, guilty, guilty,' and they started chanting, 'Lock her up, lock her up' - that's not how we do politics in this country," Sen. Al Franken of Minnesota said at a news conference in Cleveland with Democratic National Committee Chairwoman Debbie Wasserman Schulz and Sen. Cory Booker of New Jersey. "That's very banana republic."

Christie didn't just go after Clinton this week. He targeted fellow Republicans who haven't backed Trump - including Texas Sen. Ted Cruz, who spoke at the convention Wednesday but didn't endorse his former primary rival.

Christie, who said Cruz's speech Wednesday was "awful" and "selfish," continued to bash the senator Thursday, saying Cruz showed "why he is the most disliked person in either party on Capitol Hill."

In an interview Thursday with radio host Chris Stigall, former Cruz campaign manager Jeff Roe said Christie "turned over his political testicles long ago."

While Christie's decision to back Trump in February stirred speculation over whether the businessman might reward him with a White House job, the governor said Thursday that his early endorsement was intended to benefit New Jersey Republicans.

"It's about trying to position us as a minority party in a blue state to be able to have significant influence with the person who may in fact be the next president of the United States," Christie said.

He pointed out that the delegation had "pretty good seats" for the convention: "That didn't happen by coincidence."

Christie recalled his instructions to the party before the 2012 election, asking state Republicans to "keep your powder dry" before moving together to back the same candidate.

When he endorsed Mitt Romney, the eventual nominee, "that served all of us very, very well in terms of our party's influence . . . including having me be the keynote speaker in 2012," Christie said.

To New Jersey Republicans, Christie noted that his endorsement of Trump was "not without risk." But he said the relevance of the state party - which hasn't voted for a Republican president since 1988 - was at stake.

"I want you to not allow New Jersey to become a back-row player in Republican national politics," he said.

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Staff writer Jonathan Tamari contributed to this article.