Donald Trump speaks in New Mexico. REUTERS/Carlo Allegri Donald Trump repeatedly insisted without clear factual evidence that Hillary Clinton could allow between 600 million and 650 million new immigrants to enter the US.

At a series of campaign rallies on Sunday, the Republican presidential nominee claimed that Clinton "just wants to let people pour in."

"You could have 650 million people pour in and we do nothing about it," he said. "Think of it. That's what could happen. You triple the size of our country in one week."

Trump's claim about Clinton's immigration plan is unsupported by existing evidence. The Democratic presidential nominee has made immigration reform a central part of her campaign pitch, promising a pathway to citizenship for millions of immigrants living in the US, but has not proposed allowing millions more new immigrants to enter the US.

Trump's claim may reference transcripts of Clinton's 2013 speech to Banco Itau in which the former secretary of state said she envisioned a world with "a hemispheric common market, with open trade and open borders." As Politifact points out, the claim contrast with past statements in which Clinton advocated for tougher border security and deportations of violent criminals coupled with immigration reform.

Trump has a history of exaggerating Clinton's immigration claims.

The real-estate magnate has repeatedly claimed that Clinton wants to allow 600,000 Syrian refugees to seek asylum in the US, while in reality the former secretary of state has proposed accepting around 65,000.