In 2003 Rosselló made a comeback, winning the NPP's 2004 gubernatorial nomination in primaries against then-NPP President Carlos Pesquera.

He then lost the 2004 gubernatorial race to Anibal Acevedo Vilá by an unprecedented and a vigorously disputed razor-thin margin.

He earned his Bachelor of Science degree, magna cum laude at the University of Notre Dame in 1966, as well as several academic and athletic distinctions.

5-time-Mens-Champion, and also to play for Puerto Rico's team in regional championships, including the Central American and Caribbean Games.

In 1985, Rosselló was named Health Services Director for the city of San Juan by then Mayor Baltasar Corrada del Río.

Rosselló began his political career in 1988 when he ran for the office of Resident Commissioner of Puerto Rico, (the island's non-voting observer/representative in the United States Congress) losing to incumbent Jaime Fuster of the Popular Democratic Party (PPD).

These protests arose over litany of controversies that marred Rosselló's government, including the privatization of the island's utilities, massive cost overruns and contract disputes on development projects, and several corruption scandals involving top cabinet officials.

[6] He also worked to eradicate drug traffic in Puerto Rico Publics School on his campaign "Zona Libre de Drogas" (Drug-Free Zone).

He supported the congressional Young Bill, which sought to carry out a referendum in Puerto Rico to define the political status of the island.

The opposing Popular Democratic Party led a campaign to boycott the plebiscite and called the electorate to vote for the None of the Above column.

[8] In the 1996 elections he defeated rivals Héctor Luis Acevedo (PPD) who was mayor of San Juan at the time, and Representative David Noriega (PIP), winning a second term after obtaining more than one million votes and the largest victory margin since 1964.

Among the charges was the use of government funds that had been allocated for treating Puerto Ricans suffering from AIDS which were instead used to finance Rosello's political campaign.

After Clinton and Rosselló left office, the administration of the next Governor of Puerto Rico, Sila Calderón, rescinded this agreement.

Despite political grandstanding from the Calderón administration calling of an earlier withdrawal, the Navy left Vieques on May 1, 2003, the same date President Clinton and Governor Rosselló had agreed upon.

In 2003, Rosselló returned to politics and won his party's nomination for the gubernatorial candidacy in a primary election against his successor as PNP leader, Carlos Pesquera.

In the 2004 Puerto Rico Elections the PNP won majorities in both houses of the Legislature, the mayorships of 42 of the island's 78 municipalities and the Resident Commissioner post in the U.S. Congress.

However, the position of governor was given then to incumbent Resident Commissioner Aníbal Acevedo Vilá who won by razor-thin margin in a highly controversial PR Supreme Court decision that many still hold was politically motivated.

An internal power struggle within the New Progressive Party between Rosselló and McClintock led to a split within the NPP Senate delegation in May 2005.

Both González and Rios expressed their lack of concern over the reprimand and were handily renominated in the March 2008 primary and reelected in the November 2008 general election.

On April 28, 2007, Rosselló revealed to various party leaders that in March, 2006, he had signed a sworn statement assuring that he would not make a fourth run for the governorship in 2008, and that he intended to abide by the result.

During the April 25, 2007, U.S. House Subcommittee on Insular Affairs hearing on Puerto Rico's political status, he was seen treating McClintock very cordially, which suggests that the tension levels between them had eased somewhat, suggesting he may have wanted to help reunite the party as it prepares for the 2008 electoral campaign against incumbent Governor Aníbal Acevedo Vilá and assume a different non-elective role within the statehood movement to which he has devoted nearly two decades of his life.

His candidacy was contested by Luis Fortuño, the current Resident Commissioner of Puerto Rico, with whom he had shared the ballot in 2004.

On March 9, 2008, Rosselló conceded the victory to Luis Fortuño after a large margin of votes in favor of his opponent at the primaries.