They said that areas such as the shuttle's cabin door and parachute deployment areas were rigged to be operated by explosive systems and munitions experts have been deployed to deal with any debris suspected of presenting that risk.

CNN: Four compounds from shuttle can harm on contact

Democrats, raising an issue they have pressed for years, asked if part of the problem was because groups organizing under section 501(c)(4) of the tax code have operated under unclear rules since the Supreme Court in 2010 opened the door for corporations and other groups to spend unlimited amounts to influence campaigns.

WSJ: Treasury Officials Knew of IRS Probe Last June