eligibility to be elected to the presidency) may have been assured at birth by either jus sanguinis, since his parents were U.S. citizens, or jus soli, as the Panama Canal Zone was at that time (1936) a United States possession (1903–1979), or both. However, Internet talk questioned whether McCain, who was born at Coco Solo Naval Air Station in Panama, qualified as a natural-born citizen. A bipartisan legal review by Laurence Tribe and Theodore Olson, as well as a unanimous but nonbinding Senate resolution, indicate that McCain does indeed fulfill the requirement. However, University of Arizona constitutional law professor Gabriel J. Chin argues both that the Tribe-Olson opinion is unsound under current law and that McCain was actually granted citizenship by a law which was passed eleven months after McCain's birth, disqualifying him under the Constitution from natural-born citizenship and the presidency. Commenting on the Chin paper, Temple University law and citizenship expert Peter Spiro said, "No court will get close to it, and everyone else is on board, so there's a constitutional consensus, the merits of arguments such as this one aside." Catholic University law professor Sarah Duggan agreed that no legal challenge would prevail, but said only a constitutional amendment could fully resolve the question. During the general election phase of the campaign, a lawsuit by an American Independent Party member challenging McCain's eligibility was dismissed by a federal judge in San Francisco in September 2008 due both to lack of evidence and lack of standing; U.S. District Court Judge William Alsup also issued an order stating that it was "highly probable" that McCain was a natural born citizen. The McCain campaign also looked into lawsuits claiming that Barack Obama was not a natural-born citizen, but saw no evidence or chance of success behind them. Bush endorsement On March 5, 2008, President Bush welcomed McCain to the White House and officially endorsed the man who would be his party's standard-bearer in November. The endorsement was seen as helping McCain rally conservatives, and brought with it the promise of much-needed fundraising help heading in to the general election. Democrats painted a different picture, hoping to capitalize on Bush's low approval ratings. The Democratic National Committee said that McCain would offer a "third term of George W. Bush". Establishing himself McCain turned his attention to the November general election, while the Democratic primaries continued to be a battle between Clinton