Trump’s response to the caravan has escalated in recent days, along with his broader rhetoric on immigration, as the crucial Nov. 6 midterm elections near. The administration said Tuesday it would send 5,200 troops to the border by the end of this week.

“We’ll go up to anywhere between 10 and 15 thousand military personnel on top of border patrol, ICE, and everybody else at the border,” Trump said Wednesday before leaving the White House for a campaign rally.

Trump’s comments come as he also pledged to take away “birthright citizenship” from babies born to unauthorized immigrants. He clashed with House Speaker Paul Ryan earlier Wednesday, tweeting that the Republican leader “should be focusing on holding the Majority rather than giving his opinions on Birthright Citizenship,” after Ryan had criticized Trump’s proposal.

Trump has made illegal immigration a front-burner issue in the weeks before the midterm congressional elections on Nov. 6, believing it motivates his supporters to turn out to vote and creates political headaches for Democrats. As part of that effort, the president has amplified concerns about the migrant caravan, which largely consists of individuals from Honduras, El Salvador and Guatemala.

The U.S. Defense Department said in a statement on Wednesday that it expects to initially “have more than 7,000 troops” supporting the Department of Homeland Security in California, Texas and Arizona.

Customs and Border Patrol Commissioner Kevin McAleenan said Tuesday that U.S. authorities are tracking the caravan of refugees, currently estimated at around 3,500 people, as well as another group between Guatemala and Mexico of about 3,000 people.

Trump earlier Monday tweeted that “very bad people” were among the migrants seeking asylum.

Trump also on Wednesday reiterated a claim that the population of undocumented immigrants in the U.S. could be as high as 30 million. Most estimates put the total around 11 million. The only study that comes close to backing Trump’s claim is one published last month by researchers at Yale University and the Massachusetts Institute of Technology, who estimated the population as of 2016 was between 16.2 million and 29.5 million.

Trump said in an interview with “Axios on HBO” to be broadcast Sunday that he planned to issue an executive order prohibiting “birthright citizenship” for children of non-citizens and undocumented immigrants. Axios released a clip of the interview on Tuesday.

The Constitution’s 14th Amendment guarantees citizenship to anyone born in the U.S. Ryan, who is retiring from Congress, later criticized the idea of changing the law by executive order.

“You obviously cannot do that,” Ryan told WVLK in Lexington, Kentucky, on Monday. “I’m a believer in following the plain text of the Constitution and I think in this case the 14th Amendment is pretty clear, and that would involve a very, very lengthy constitutional process.”

Earlier on Wednesday, Trump claimed that a clause in the 14th Amendment that conveys citizenship only to people “subject to the jurisdiction” of the U.S. excludes children of undocumented immigrants. Legal scholars on both the right and left disagree with him and say that the matter is settled law.