Newt Gingrich predicted that the Republicans will hold on to the House of Representatives and "dramatically increase" their number of senators in the upcoming midterm elections.
Polls show the Democrats have a lead over Republicans in the final weeks before the vote. According to FiveThirtyEight's polling tracker, which has a running average of all major polls, Democrats are on 49.7 percent and the Republicans are on 41.3 percent.
"This election is a life-and-death struggle with a left-wing movement which wants to radicalize America," Gingrich, the Republican former House speaker, told Sean Hannity on his Fox News show Wednesday night.
"I have a prediction for you. Sometimes politicians and their consultants and everybody does all this planning, and then history just picks things up and changes everything.
"I think two words are going to define the night of the 2018 election in the next three weeks. One is Kavanaugh and the other is caravan."
Republicans were galvanized by the bitter political fight to confirm President Donald Trump's nominee to the Supreme Court, Judge Brett Kavanaugh, amid allegations of sexual assault made against him by women he knew at high school and in college.
The confirmation process became a proxy war between Republicans and Democrats. Kavanaugh was eventually confirmed but many Democrats vowed to fight on even as he took his place on the Supreme Court.
There is also a caravan of people travelling up through Central America fleeing poverty, crime and war and seeking to enter the U.S., a touchstone of the immigration issue that divides American politics.
Democrats balk at Trump and the Republican Party's hardline stance on immigration, such as the border wall, family separations, and his crackdown on sanctuary cities.
"The combination of anger over how the left smeared, engaged in character assassination, lied, used bullying tactics with Judge Kavanaugh is going to be one part of this," Gingrich told Hannity.
"And the degree to which the left is eager to have 3,000 people in a caravan cross the American border, break American law, recognizing that if that happens, the next caravan will be even bigger, and the caravan after that will be even bigger.
"I think the American people are going to reject both the way they treated Kavanaugh and the way they are dealing with the border. I think those will end up being the reasons the Republicans keep the House and dramatically increase the number of Senators they have."
