Washington DC - President Donald Trump defended his record Tuesday in a final TV phone-in pitch to voters on the morning of midterm elections, claiming he had rebuilt the country through his immigration crackdown, war on Iran, and tariff policy.

"We have to keep America great. We're great now. We were terrible two years ago," Trump told the Fox & Friends show as Americans voted in elections that could see his Republican Party lose control of Congress.

Polls predict Democrats will win the House of Representatives and have a shot at the Senate, and Trump, whose own ratings have plunged, targeted his last-minute message at his right-wing base.

"We were a laughing stock all over the world," he said. "The leaders of other countries didn't even take us seriously. They thought we were fools, and we're hot now. We're the hottest country in the world. We're respected by everybody.

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"We're going to keep it that way and get better."

In his second term, Trump has dramatically cut the number of migrants crossing the US border from Mexico and launched a war on Iran that has caused gas prices to soar for Americans.

"When I took over, the border was open. We were having millions and millions of people pour in, many criminals and murderers," he said, repeating his often baseless or exaggerated claims.

"They were released from jails from the Congo in Africa, from all over South America, from Asia. They were pouring into our country. It was just a horrible sight, and they were very dangerous."

"The inflation is solved," he added, "And the Hormuz Strait, we have total control of it with the Navy blockade (on Iran). I mean, everything's going good.

"Car companies are pouring in because they don't want to pay tariffs."