Since March, Treasury Secretary Jacob Lew has been making a series of moves to keep the government operating without going over the current limit while appealing to Congress to raise the borrowing limit. Republicans control both the House and Senate, and more conservative GOP lawmakers would like to use the need to raise the borrowing limit as leverage to force President Barack Obama to shift his policies in such areas as health insurance and immigration. It was a standoff over raising the debt limit in August 2011 that prompted the first-ever downgrade of the nation's credit rating by Standard & Poor's. [...] in October 2013, a dispute over the budget prompted a 16-day partial government shutdown.