(New throughout, adds comments of U.S. lawmakers at conference in Houston)
By Ernest Scheyder
HOUSTON, March 10 (Reuters) - Two top U.S. senators voiced skepticism on Friday about a possible border tax, worrying it could boost prices for gasoline and other consumer goods.
President Donald Trump is studying a Republican proposal in the House of Representatives for a border tax adjustment system that would levy a 20 percent tax on all imports while exempting exports.
The measure is heavily opposed by Canada, which relies on the United States as its largest trading partner.
Opponents of the measure say it could do more harm than good, viewpoints echoed on Friday by John Cornyn of Texas and Lisa Murkowski of Alaska at the CERAWeek conference in Houston, the world's largest gathering of energy executives and regulators.
"The more I've looked at it, the more I worry the assumptions upon which it's based are unproven," said Cornyn, the No. 2 Republican in the Senate. "I also worry about the politics of this, raising prices on consumers."
Texas and Alaska are large oil producers and any fresh tariff could harm exports of crude oil and potentially imports of a myriad consumer goods, concerns both senators said were on their minds.
"I'm not really interested in anything that's going to be increasing the price of gasoline for folks in Alaska," Lisa Murkowski, chair of the Senate's energy and natural resources committee, said at the conference.
"It's something we need to look at critically and weigh and understand."
Both senators said they supported changes to the North American Free Trade Agreement, or NAFTA, but opposed scrapping it entirely.
"NAFTA has been a benefit to this region of the country and the country as a whole," said Cornyn. "NAFTA's not a dirty word in Texas." (Reporting by Ernest Scheyder; Editing by David Gregorio)