Mexico's Senate on Tuesday moved a step closer to passing reforms to open up the country's oil industry to private investment, sending a draft bill to the floor of the upper chamber to speed up the approval process. The bill, backed by the ruling Institutional Revolutionary Party (PRI) and the opposition conservative National Action Party (PAN), would mark the biggest strategic shift since the world's no. 10 oil producer nationalized the sector 75 years ago. It aims to let private firms partner with ailing state oil firm Pemex via profit-sharing, risk-sharing and service contracts as well as licenses. Senate committees overseeing the bill gave it general approval on Monday before beginning a protracted debate on reservations raised by leftist lawmakers trying to derail it.