UPDATE: Ted Cruz has concluded speaking on the Senate floor after 21 hours and 19 minutes:
21 hours, 19 minutes for freedom, free markets, transparency, deliberation & constitutional principles. Thank you @SenTedCruz
— Michelle Malkin (@michellemalkin) September 25, 2013
Ted Cruz is on the Senate Floor taking a stand for defunding Obamacare:
Senator Ted Cruz is making the argument for why the Senate should vote on the House Continuing Resolution that funds the government and defunds Obamacare. He intends to speak, as he said, until he is no longer able to stand.