washington u.s. treasury secretary steven mnuchin urge congress wednesday raise federal debt limit lawmakers start august recess avoid high interest cost taxpayers market uncertainty potential default maintain u.s. creditworthiness utmost importance unite state must pay bill time mnuchin tell senate appropriations subcommittee suggest past base upon best estimate time fund september urge congress take leave recess mnuchin say however little sign congress would heed mnuchin call least moment house representatives due start recess friday hint movement issue senate consume try pass healthcare overhaul bill could leave debt limit unaddressed congress return sept. perhaps one month treasury run real risk able pay obligations last extension federal borrow limit expire march total debt around 20 trillion treasury extend ability issue debt employ extraordinary cash management measure include defer reinvestments federal employee pension fund short-term treasury bill market grow nervous potential treasury exhaust borrow capacity mid-october send yield high crush demand recent 3-month bill auction situation cost taxpayers money stoke market uncertainty say mnuchin former banker hollywood film financier right effectively oppose borrow market low rat borrow make trust fund whole slightly high rat real cost say also imply cost uncertainty market long wait uncertainty be senator jam lankford republican say hear best estimate derive work treasury officials use extraordinary measure would amount 2.5 billion largely government would cover interest owe affect pension fund mnuchin dispute estimate lawmakers show vary level concern capitol hill week senate focus try pass bill repeal replace affordable care act know obamacare right focus obamacare say senator ted cruz ask tuesday lack action debt limit concern cruz lead fellow republicans 2013 demand spend cut part fiscal fight lead 16-day partial government shutdown another fiscal conservative senator david perdue say however would prefer congress stay session august deal raise debt ceiling add get get do senate majority leader mitch mcconnell want pass debt ceiling increase time nail spokesman say u.s. treasury 's mnuchin urge congress lift debt limit recess