Question: Heather R. Mizeur lost the Democratic primary to what American lawyer and politician, who is currently serving as the U.S. Representative for Maryland's 4th congressional district?

Context articles: Debbie Halvorson
Al Green (politician)
Reshma Saujani
Carolyn Cheeks Kilpatrick
Joe Kennedy III
Gary Peters (politician)
Rick Nolan
Anthony G. Brown
Heather Mizeur
Frederick R. Lehlbach

Deborah L. "Debbie" Halvorson (born March 1, 1958) is the former U.S. Representative for  's 11th congressional district , serving from 2009 until 2011.
 Previously, she served in the Illinois Senate from 1997 through 2009.
 She is a member of the Democratic Party.
 In September 2011, she filed to run in the newly redistricted 2nd congressional district but was defeated in the Democratic primary by the incumbent, Jesse Jackson, Jr.
Al Green (born September 1, 1947) is an American lawyer, and politician who is currently serving as the U.S. Representative from Texas's 9th congressional district, serving since 2005.
 The district includes most of southwestern Houston, including most of that city's share of Fort Bend County.
 It also includes most of Missouri City.
 Green is a member of the Democratic Party.
Reshma Saujani is an American lawyer and politician.
 She is the founder of the tech organization Girls Who Code.
 She was previously the Deputy Public Advocate at the Office of the New York City Public Advocate.
 Saujani lost the 2010 Democratic primary (19%-81%) for the U.S. House of Representatives in New York's 14th congressional district against incumbent Congresswoman Carolyn B. Maloney.
 Saujani was the first Indian-American woman (and the first South Asian American woman) to run for Congress.
 She ran as a Democratic candidate for New York City Public Advocate in 2013, coming third in the primary.
Carolyn Jean Cheeks Kilpatrick (born June 25, 1945) is an American politician who was U.S. Representative for  's 13th congressional district from 1997 to 2011.
 She is a member of the Democratic Party.
 In August 2010 she lost the Democratic primary election.
 She was replaced by Hansen Clarke in January 2011.
Joseph Patrick "Joe" Kennedy III (born October 4, 1980) is an American lawyer and politician.
 He is currently serving as the U.S. Representative for Massachusetts 's 4 congressional district since 2013.
 He is a Democrat whose district extends from the western suburbs of Boston to the state's South Coast.
 A son of former U.S. Representative Joseph P. Kennedy II, he worked as a Peace Corps volunteer and as an assistant district attorney in the Cape and Islands and Middlesex offices before his election to Congress.
Gary Charles Peters (born December 1, 1958) is an American politician and businessman who is the junior United States Senator from Michigan.
 A member of the Democratic Party, he was the U.S. Representative for Michigan 's 14 congressional district from 2013 until his election to the Senate.
 The district includes the eastern half of Detroit, as well as the Grosse Pointes, Hamtramck, Southfield and Pontiac.
 He previously represented Michigan 's 9 congressional district from 2009 to 2013.
 Following the redrawing of congressional district boundaries after the 2010 United States Census, Peters defeated fellow Congressman Hansen Clarke in the Democratic primary and won re-election in the newly redrawn 14th District.
Richard Michael Nolan (born December 17, 1943) is an American politician and member of the Minnesota Democratic–Farmer–Labor Party who has been the U.S. Representative for Minnesota's 8th congressional district since 2013 and previously served as the U.S. Representative for Minnesota's 6th congressional district from 1975 to 1981.
Anthony Gregory Brown (born November 21, 1961) is an American lawyer and politician, who is currently serving as the U.S. Representative for Maryland's 4th congressional district.
 He previously served as the eighth Lieutenant Governor of Maryland, from 2007 to 2015.
 He was elected as lieutenant governor in 2006 on the Democratic ticket with Governor Martin O’Malley, and both were reelected in 2010.
 In 2014 he ran unsuccessfully for Governor of Maryland, losing to Larry Hogan.
 Brown previously served two four-year terms in the Maryland House of Delegates, representing Prince George's County.
 He is currently a Colonel in the United States Army Reserve, having served in the U.S. Army for nearly thirty years.
 While lieutenant governor, Brown was one of the two highest-ranking elected officials in the nation to have served a tour of duty in Iraq.
Heather R. Mizeur ( ; born December 6, 1972) is an American politician and member of the Democratic Party from the state of Maryland.
 She has served as a member of the Maryland House of Delegates from January 10, 2007 to January 14, 2015, representing the 20th district in Montgomery County.
 She was a candidate for Governor of Maryland in the 2014 election but lost the Democratic primary to Lieutenant Governor of Maryland Anthony G. Brown.
Frederick Reimold Lehlbach (January 31, 1876 – August 4, 1937) was an American lawyer and politician.
 As a Republican, Lehlbach served as the U.S. Representative for New Jersey's 10th congressional district from 1915 to 1933 and as the representative from New Jersey's 12th congressional district from 1933 to 1937.
 Lehlbach was also the nephew of Herman Lehlbach, a former U.S. Representative from New Jersey's 6th congressional district who served from 1885 to 1891.