This "nonpartisan, nonprofit, consumer advocate" site monitors the factual accuracy of statements from major U.S. political figures. The site is sponsored by the Annenberg Public Policy Center of the University of Pennsylvania.
"Media Matters for America is a web-based, not-for-profit, 501 (c)(3) progressive research and information center dedicated to comprehensively monitoring, analyzing, and correcting conservative misinformation in the U.S. media." - From MediaMatters website.
"OpenSecrets.org is your nonpartisan guide to money’s influence on U.S. elections and public policy." Categories for politicians and elections, influence and lobbying, and news and analysis. Also the "Capital Eye" blog. From the Center for Responsive Politics.
PolitiFact is a project aimed at bringing the truth in politics. PolitiFact's reporters and editors fact-check statements from the White House, Congress, candidates, advocacy groups and more, rating claims for accuracy on their Truth-O-Meter.
"This independent, nonpartisan website run by professional researcher and writer David Mikkelson researches urban legends and other rumors. It is often the first to set the facts straight on wild fake news claims."
"The Sunlight Foundation is a national, nonpartisan, nonprofit organization that uses civic technologies, open data, policy analysis and journalism to make our government and politics more accountable and transparent to all." - From the organization website.