The lineup is getting thin for the President Donald Trump backed Great American State Fair in Washington D.C. with country singer Martina McBride becoming the latest performer to cancel. Reflecting a sentiment from other musicians who have bailed, McBride expressed in a statement put out on social media that she was misled to believe the fair was a nonpartisan event. McBride, a Grammy-nominee and force in 1990s country music behind 1994’s “Independence Day,” said she wanted to “clear the air” before announcing that she would not be performing at the event. “I was presented with an opportunity to perform at a nonpartisan event but that turned out to be misleading,” she said. “I asked lots of questions and was assured this was a nonpartisan event that was meant to celebrate ALL 50 states.…