House Minority Leader Nancy Pelosi, D-Calif., likened the Republican tax package to Frankenstein's monster and warned that the bill will come back to haunt Republicans next year in the 2018 midterms.

"It's a Frankenstein," Pelosi said of the bill during her weekly press conference. "Anybody who's familiar with Frankenstein knows it was a creation, a monster that was created."

"Do you know the ending of the Mary Shelley's story? The monster comes back to destroy," she said.

Throughout, Pelosi talked up Democratic chances of retaking the House in the fall and reiterated that the tax bill will be a major reason for their potential success. She said that Republicans are acting like a group that know their influence will not last beyond next November.

"They're acting like people who know that their power is short-lived," Pelosi said. "This is really a big opening. The door is open. The president's [approval] numbers are in the 30s. I think, probably, his numbers and the support for the tax bill are probably similar."

Pelosi said that she doubted polls that show their lead over Republicans to be a solid double-digit lead. The latest RealClearPolitics average shows Democrats to be leading Republicans on the generic congressional ballot by 13 points. One poll shows Democrats with as much as an 18-point lead over their Republican counterparts.

"I'll take half of that, nine, to win the Congress," Pelosi said. "It will be an interesting year ... It's an opportunity."