but as nbc's kelley o'donnell t explainst decision is setting up a legal showdown. >> reporter: a downpour didn't dampen the president's reaction. >> big ruling, a great ruling for our country. >> reporter: following a solemn visit to arlington national cemetery, today president trump spoke for the first time about texas federal court overturning obamacare anticipating a higher court showdown. >> we'll sit down with the democrats, if the supreme court upholds. we'll sit down with the thmocrats and get great he care for our people. >> reporter: that sudden call for cooperation at odds with years of raw political conflict. >> and we've decimated obamacare. >> health care was on the ballot and health care >> reporter: but friday, a texas federal judge upended the volatile obamacare debate. a 55-page rulingeclared the key requirement to buy health insurance, the individual ma ate, unconstitutional after congress willed some mandates tax penalty last year. without it, the judge ruled the entire law is now invalid. threatening many popular provisions like protection for pre-existing conditions,