Bangor Daily News photo by Seth Koenig

Independent U.S. Sen. Angus King on Tuesday rejected Donald Trump’s argument that the United States should close its borders to immigrants.

King, the former governor whom Maine voters overwhelmingly elected to the Senate in 2012, said on CNN’s “New Day” program, which was subsequently summarized by The Hill, that ending immigration would be a “terrible loss” and that doing so would cause irreparable damage.

“There are gaps in the system and you have to look at them,” said King. “You also have to look at the law of large numbers. There are going to be problems. You’re never going to reach perfection. If we have to wait until we are satisfied that the system is absolutely perfect … then you wait forever.”

King said about half of illegal immigrants have merely overstayed their visas and that the vast majority of immigrants mean no harm.

“Everyone from Albert Einstein to Donald Trump’s ancestors and mine and yours came in through the immigration system,” said King. “To shut everything down all of a sudden I think would be at a terrible cost to the country, not commensurate with the risk that would be allayed.”

King’s comments come as Trump has made immigration a controversial yet central theme in his presidential campaign. Trump has called for a range of crackdowns on illegal immigrants, including suggesting that as president he would build a wall between the United States and Mexico and advocating that the country’s roughly 11 million illegal immigrants — including asylum seekers working their way through the immigration process — should be deported. On Monday, he suggested that the “extremely open immigration system” was to blame for the weekend’s bombings in Manhattan.

Officials have said the prime suspect in the bombings has lived in the U.S. since he moved here from Afghanistan with his parents as a young boy, though that has not been confirmed by the Department of Homeland Security.

Democratic nominee Hillary Clinton takes a sharply different stance on immigration and along with President Barack Obama’s administration has vowed to keep the U.S. open to refugees and asylum seekers, as is required in international law.

King caucuses with Democrats in the Senate, which makes his critical comments about Trump perhaps less surprising. However, Trump has taken considerable fire from within his own party for his immigration proposals, including from Republican U.S. Sen. Susan Collins of Maine. In August, Collins criticized Trump for what she called “disparaging” remarks he made about Maine’s Somali population during a campaign stop in Portland.

“Mr. Trump’s statements disparaging immigrants who have come to this country legally are particularly unhelpful,” said Collins. “Maine has benefited from people from Europe, the Middle East, Asia and increasingly, Africa, including our friends from Somalia.”

Both Collins and King have said they won’t vote for Trump for president. King has endorsed Clinton while Collins has said she does not intend to vote for either major-party candidate.