Bret Baier will interview Secretary Hillary Clinton tonight on Special Report at 6:00 ET on Fox News Channel.

The sit-down comes a day after Clinton won enough delegates to clinch the Democratic Party nomination, scoring primary victories in New Jersey and California. 

Previewing the big interview, Baier told Bill O'Reilly that Clinton has "real problems and vulnerabilities" heading into the general election, citing her high negative poll numbers.

He said that she will have to find a message to appeal to Bernie Sanders' supporters and try to win over "disaffected Republicans."

Baier said he's looking forward to seeing whether Clinton gets a bump in the polls against Trump following his controversial criticism of a Mexican-American judge. 

Mrs. Clinton sat down with Baier at a town hall event in Detroit in March, where she was pressed on the information contained on her private email server. 

Clinton also sat down for an interview in 2014 with Bret and Greta Van Susteren, where she was asked about Benghazi and her statements in the aftermath of the attack.

Watch Bret discuss tonight's must-watch sit-down above.

Bret Challenges Clinton on Emails: 'Was Your Claim About Classified Info Inaccurate?'

Gutfeld: Trump Just Keeps Digging the Hole Deeper

Hillary Meets Media in CA: No Questions Asked About Emails