Chuck Grassley Criminal sentencing bill tests McConnell-Grassley relationship Majority of GOP senators to attend Trump convention The Trail 2016: It ain't over till it's over MORE Mitch McConnell Criminal sentencing bill tests McConnell-Grassley relationship Majority of GOP senators to attend Trump convention Five panels to grill FBI on Clinton MORE in a big way this Congress, having implemented the leadership's strategy of blocking President Obama's judicial picks. Polls suggest the Supreme Court fight has taken a toll on Grassley, who may be in for the toughest reelection fight of his career.