Question: What position did Michael Platt Jr originally hold working for the politician representing Tennessee's 7 congressional district?

Context paragraphs:
Mike Capuano: Michael Everett Capuano ( ; born January 9, 1952) is an American politician who serves as the U.S. Representative for Massachusetts 's 7 congressional district .  A member of the Democratic Party, his district includes the majority of Boston, as well as parts of Cambridge and other communities immediately north and south of Boston.  Prior to being elected to Congress he served as an Alderman and later Mayor of Somerville.

Thomas Dickens Arnold: Thomas Dickens Arnold (May 3, 1798 – May 26, 1870) was an American politician who served two terms in the United States House of Representatives, representing Tennessee's 2nd district from 1831 to 1833, and the 1st district from 1841 to 1843.  A staunch opponent of Andrew Jackson, he spent his first term in Congress trying to thwart the Jackson Administration's agenda, and subsequently helped establish the Whig Party in Tennessee.  He was twice gerrymandered out of office by Jackson's allies in the state legislature.

Isaac Thomas: Isaac Thomas (4 November 1784 – 2 February 1859), was an American politician representing Tennessee in the United States House of Representatives.

Lee Harris (politician): Lee Ardrey Harris (born August 1978) is a law professor who currently serves as a TN State Senator, representing Tennessee's 29th district.  Prior to his election to the state Senate, Harris served on the Memphis City Council, representing District 7.  He was born and raised in Memphis, and studied at Morehouse College, followed by Yale Law School.  In 2014 he was elected to the Tennessee Senate replacing Ophelia Ford.  He was elected in November 2014 by the Democratic Senate Caucus of the Tennessee State Senate to the leadership position of Senate Minority Leader.  He is the first black lawmaker of either party to hold a leadership position in the Tennessee State Senate.

Michael Platt: Michael Platt (born 23 March 1984) is a rugby league player who plays for the Salford Red Devils; he joined the Salford Red Devils in April 2014 and is contacted until the end of the 2014 season following a successful trial with the Superleague club. . Michael joined the Red Devils following 3 appearances with the North Wales Crusaders in 2014.  Platt's 1st choice position is Full Back but he has been more effective at Centre for the Bradford Bulls winning the 'Rugby League World Centre of the Month' for August.

Collin Peterson: Collin Clark Peterson (born June 29, 1944) is an American politician, member of the Minnesota Democratic–Farmer–Labor Party, the U.S. Representative for Minnesota 's 7 congressional district , and the most senior representative from Minnesota, serving since 1991.  He is the ranking member of the House Committee on Agriculture and the dean of the Minnesota congressional delegation.  A conservative Democrat, his district, Minnesota's largest and most rural district, includes most of the western area of the state, including Moorhead, Fergus Falls, Bemidji, Detroit Lakes, Thief River Falls, Willmar, Marshall, and Alexandria.

Michael Platt Jr.: Michael Richard Platt Jr. (born 1974) is an American political aide and government official who is currently the Assistant Secretary of Commerce for Legislative and Intergovernmental Affairs in the administration of U.S. President Donald Trump.  Prior to assuming this position, he was chief of staff for U.S. Representative Marsha Blackburn of Tennessee's 7th congressional district.

Marsha Blackburn: Marsha Blackburn (née Wedgeworth; born June 6, 1952) is an American politician and former businesswoman.  A member of the Republican Party, she represents southwest Tennessee 's 7 congressional district in the United States House of Representatives.  She has served as chair on Subcommittee on Communications and the Internet since 2017.

Pat Meehan: Patrick Leo Meehan (born October 20, 1955) is a Republican member of the United States House of Representatives, representing Pennsylvania 's 7 congressional district since January 3, 2011.  The district includes parts of Delaware County, Chester, Montgomery County, Berks and Lancaster.  He succeeded Democrat Joe Sestak, who ran unsuccessfully for the United States Senate.

Richard W. Austin: Richard Wilson Austin (August 26, 1857 – April 20, 1919) was an American politician, attorney and diplomat.  A Republican, he served in the United States House of Representatives from 1909 to 1919, representing Tennessee's 2nd district.  Prior to his congressional tenure, he worked as a United States Marshal from 1897 to 1906, and served as the U.S. consul to Glasgow, Scotland, from 1906 to 1907.

Supporting paragraphs: Michael Platt Jr. Marsha Blackburn
Answer: chief of staff