Rep. Chris Van Hollen (D-Md.) and state Del. Kathy Szeliga (R-Baltimore County) (Mark Gail (left) and Bill O’Leary/The Washington Post)

Rep. Chris Van Hollen (D-Md.) leads Maryland state Del. Kathy Szeliga (R-Baltimore County) by a wide margin in the race to replace retiring Sen. Barbara A. Mikulski (D-Md.), according to a Maryland poll released Tuesday.

The survey, conducted by Annapolis-based OpinionWorks, shows that 55 percent of likely Maryland voters would cast their ballots for Van Hollen, compared with 26 percent for Szeliga, who is the state House minority whip.

Van Hollen’s lead is greatest in Montgomery and Prince George’s counties, where he is ahead of Szeliga by 60 points and 67 points, respectively. Even in his opponent’s home jurisdiction of Baltimore County, the congressman leads by 17 points.

Szeliga’s strongest numbers were on the Eastern Shore, a Republican stronghold, where she leads by 13 points, and in Western Maryland, where she is ahead by four points.

In positive news for Maryland Republicans, the poll showed that Gov. Larry Hogan’s (R) already lofty popularity level climbed even higher, with 71 percent of respondents saying they approve of the job he is doing. A Goucher College poll in February showed the governor with a 63 percent approval rating.

Hogan’s numbers were strong even in heavily Democratic jurisdictions. Seventy-two percent of Baltimore respondents said they approve of the job he is doing, along with 65 percent of respondents in Prince George’s County and 52 percent in Montgomery County.

OpinionWorks interviewed 754 likely voters for the poll, which was first reported by the Baltimore Sun. The survey was conducted from Aug. 18 to 30 and includes a margin of error of plus or minus 3.6 percentage points.