Senate Majority Leader Mitch McConnell (from left), Senate Minority Leader Harry Reid and House Speaker John Boehner have reasons to watch the Supreme Court case closely — and to worry about its outcome. Drew Angerer/Getty Images hide caption

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President Obama has said he will veto the Keystone XL pipeline project, which passed in the Senate on Wednesday. Historically, political scientists say, 90 percent of veto threats are issued behind the scenes, but Obama has issued nine veto threats so far — in public. Mandel Ngan/AFP/Getty Images hide caption

itoggle caption Mandel Ngan/AFP/Getty Images