U.S. House of Representatives Speaker John Boehner warned rank-and-file Republicans in a conference call on Thursday against using the threat of a government shutdown to stop the implementation of Obamacare, according to people on the call. On the call, Boehner reminded Republicans of the political backlash their party suffered when the government shut down in 1995-1996, according to one person on the call. A House Republican aide, however, emphasized that no final decision has been made on whether to pursue a strategy advocated by some in the party of denying funds for Obamacare. Republicans agree strongly on their opposition to Obamacare, viewing the law as a burden to businesses that will cost jobs. But the party has been roiled by heated debate over the strategy for trying to stop the law.