Former Vice President Joe Biden widened his lead in the 2020 Democratic presidential primary to 19 points over second-placed Sen. Elizabeth Warren (D-Mass.), according to the latest Quinnipiac poll released Monday.

Biden widened his lead after the previous Quinnipiac Poll on July 2 showed Biden's lead over then second-placed candidate Sen. Kamala Harris (D-Calif.) had shrunk to just two points shortly after the first Democratic primary debate.

Warren placed second in the latest Quinnipiac poll with 15 percent support, up from third in the July 2 poll.

Warren was followed closely by Sen. Kamala Harris (D-Calif.), at third with 12 percent support, and Sen. Bernie Sanders (I-Vt.), at fourth with 11 percent support.

In the July 2 poll, Harris had placed second, with 20 percent support, after confronting Biden over the former vice president's policy opposition to federally mandated busing during desegregation, while Warren was at third, with 14 percent support.

South Bend, Ind., Mayor Pete Buttigieg (D) again placed fifth, polling at 6 percent.

All other candidates in the crowded field are polling at 2 percent or less.

The latest Quinnipiac poll was released just ahead the second presidential primary debates set to take place over Tuesday and Wednesday.

The Democrats will face-off again in two debates this week, 10 on Tuesday and 10 on Wednesday, in Detroit.

Sanders and Warren will be on the same stage the first night, while Biden and Harris will again be on stage together at Wednesday's debate.

The poll was conducted from July 25 to 28 and surveyed 1,306 voters nationwide. There is a 3.4 percentage point margin of error.