President-elect Donald Trump's pick to lead the Department of Defense said Tuesday that he was "grateful" to be nominated as House Republicans introduced a must-pass spending bill that included language designed to expedite his confirmation.

Retired Marine Gen. James "Mad Dog" Mattis briefly joined Trump on stage at the president-elect's "Thank You" rally in Fayetteville, N.C.

"I’m grateful for the opportunity to return to our troops, their families, the civilians at the Department of Defense," Mattis said in brief remarks. "I know how committed they are and devoted they are to the defense of our country [and] the defense of our Constitution. And with our allies strengthened and with our country strengthened, I look forward to being the civilian leader, so long as Congress gives me the waiver and the Senate votes to consent."

"You're going to get that waiver," Trump said as Mattis left the microphone. "If you don’t get that waiver, there are going to be a lot of angry people."

Mattis retired from the military in 2013. However, since federal law requires the secretary of defense to be off active duty for at least seven years, Congress would have to approve a waiver allowing Mattis to lead the Pentagon.

Shortly before Trump took the stage, House Republicans included a proposal to expedite the waiver in legislation to keep the government funded into next spring.

The bill would prevent the government from shutting down this weekend and buy several months for the new Congress and incoming Trump administration to wrap up more than $1 trillion worth of unfinished agency budget bills.

However, it also includes language meant to force Senate Democrats to consider whether to oppose the entire spending bill over Mattis' confirmation, risking a government shutdown over the matter.

The legislation requires Mattis to receive 60 Senate votes to receive the waiver. However, the legislation would limit debate on the measure to 10 hours.

For Mattis to receive the waiver, at least eight Senate Democrats would have to join 52 Senate Republican to approve it.

Trump himself was less bombastic Tuesday evening than at a similar rally last week in Cincinnati. The president-elect attempted to strike more of the healing notes traditionally delivered in the weeks after a bruising campaign. He even stopped the crowd when it started to boo the media.

"We will defend American jobs. We have to look at it almost like a war," Trump thundered. "We want the next generation of innovation and production to happen right here in America.

"We will heal our divisions and unify our country. When Americans are unified there is nothing we cannot do -- nothing!" he added. "I'm asking you to dream big again as Americans. I'm asking you to believe in yourselves."

Fox News' Chad Pergram and the Associated Press contributed to this report.