President Donald Trump has ramped up his attacks against Democratic vice presidential nominee Kamala Harris, as he continues to face an uphill battle for a second term. 

At a rally Thursday in Michigan, Trump characterized Harris as “the most liberal person in the U.S. Senate.” During a North Carolina campaign event earlier in the week, Trump said “nobody likes” Harris, and claimed that it “would be an insult to our country” if she becomes the first female president. 

Trump has repeatedly mispronounced Harris’ first name and stoked a conspiracy theory that she is not eligible to be vice president. He has also given her a nickname, “phony Kamala.”

Harris, who has served as California’s junior senator since 2017, has been a strong critic of Trump during her political career. She is known for her tough questioning at Senate hearings, including an exchange with Supreme Court Justice Brett Kavanaugh.

More recently, Harris has criticized Trump over his response to the ongoing COVID-19 pandemic. She has called it “outrageous” that Trump admitted to downplaying the virus in a recorded interview with famed journalist Bob Woodward. 

Trump’s new attacks against Harris come as the president has fallen behind in polls to Democratic nominee Joe Biden. Trump has attempted to paint Biden as mentally deficient and said he is a “trojan horse for socialism.”

A poll released Thursday by Monmouth University showed Biden with a 7-point nationwide lead over Trump, 51% to 44%.