Parga was finally elected to the post in a special election held in April 11, 1999 to fill the vacancy left by former Senate President Roberto Rexach Benitez' resignation. At the 2000 general elections, he was reelected to his seat and chosen as Senate Minority Whip. Parga was re-elected at the 2004 elections. However, when the defeated 2004 PNP gubernatorial candidate, Pedro Rosselló, gained a seat in the Senate and tried to oust President Kenneth McClintock, Parga was one of the six Senators that supported the latter and refused to support Rosselló. For their loyalty, they became known as "Los Auténticos", which in turn, ignited a series of schemes to coerce them into supporting Rosselló. In November 2005, it was revealed that the Puerto Rico Capitol's surveillance camera system was allegedly misused to blackmail fellow Senator Carlos Díaz, one of the so-called "Auténticos". McClintock appointed Parga to chair the tripartisan Blue Ribbon Committee looking into the matter. His refusal to cover-up sworn statements suggesting administrative irregularities in the administration of the House of Representatives triggered the New Progressive Party directorate to recommend his expulsion, along with Senate President Kenneth McClintock. The party recommended the expulsion of the six Senators in March 2006. According to McClintock, this recommendation was rejected by a General Assembly in August 20, 2006. Within the Senate, he presided the Committee on Consumer Affairs and Government Reports. As a result of the May 2005 split within the majority delegation, he assumed the chairmanship of the Federal, Industrial and Economic Affairs Committee of the Senate and of the Cordova and Fernos Congressional Internship Joint Committee. After Senator Héctor Martínez resigned the chairmanship of the Senate's Public Safety Committee, Parga was appointed its acting chair by the Senate President. On July 5, 2007, Parga announced that, rather than file for reelection under the PNP banner, he would aspire to become the first independent candidate to win an election to the Senate and put all his Senate leadership positions at McClintock's disposal. The Senate President immediately reiterated his trust in him, although he would no longer appear in the slate of PNP candidates. In November 2008 he was not reelected while running as an independent. Actually, as a political analyst, Parga has not held his punches when commenting on Puerto Rico's status and politics issues. In 2010, Parga said in an interview that "being a legislator in this island is worth nothing.