Watch: McConnell blasts immigration move as an Obama legacy project

Incoming Senate Majority Leader Mitch McConnell (R-Ky.) on Thursday accused President Barack Obama of pursuing his controversial executive action on immigration not to help the country, but to secure some kind of legacy for his presidency.

"Just as with Obamacare, the action the president is proposing isn't about solutions, it isn't about compassion," McConnell said on the Senate floor. "It seems to be about what a political party thinks would make for good politics."

"It seems to be about what a president thinks would be good for his legacy," he added. "Those are not the motivations that should be driving such sweeping action, and I think the president will come to regret the chapter history writes if he does move forward."

Obama is expected to outline his unilateral immigration plan in a Thursday night address to the nation. Obama is expected to propose steps that would give some form of legal status to up to five million illegal immigrants, and may also expand rules so that an entire family could be covered by a single green card.

Republicans have warned that going around Congress will make it impossible for the GOP-led House and Senate next year. Many GOP members have proposed legislation that would defund Obama's effort to impose immigration changes, but it's not clear so far whether and how Republicans might pursue that idea.

Still, McConnell warned that if Obama acts, Congress will act next year once Republicans take over.

"If President Obama acts in defiance of the people and imposes his will on the country, Congress will act," he said. "We're considering a variety of options. But make no mistake, make no mistake, when the newly elected representatives of the people take their seats, they will act."

McConnell said it makes no sense for Obama to act alone, given the midterm election that saw huge Republican gains at the federal and state levels.

"The American people clearly sent a message, nobody missed it," he said. "They said they want to see us working together. They said they want to see more serious ideas passed through Congress."

"What they didn't say they wanted to see was the president side-stepping the very representatives they just elected," McConnell added.

Several Republicans have noted that Obama himself has made several statements over the last few years in which he's said he does not have the legal authority to act on his own. McConnell said Obama now appears to be on the verge of contradicting himself.

"The president's previous answers seemed to be unequivocal: he lacked the legal authority to act, according to the president himself," he said. "He knows this is not how democracy is supposed to work, because he told us so himself."

Nonetheless, some Republicans have said Obama's decision will show he is now Emperor of the United States.