Likely presidential hopefuls Hillary Clinton and Chris Christie are playing to their energy industry constituents this week, albeit from opposite ends of the spectrum. Clinton will speak to a group of "clean energy" leaders Thursday afternoon in Las Vegas, while Christie, the Republican governor of New Jersey, is appealing to oil and gas developers.

Clinton, a Democrat, and Christie have yet to formally declare their intentions to vie for the U.S. presidency in 2016. (Nor has anyone else.) But both are considered likely contenders and are assumed to be laying the groundwork for campaigns.

Clinton, the former first lady, New York senator and secretary of state, will deliver the keynote speech at Thursday’s Clean Energy Summit, a daylong event hosted by Senate Majority Leader Harry Reid, D-Nev. (The speech will be broadcast live at 3:50 p.m. PDT.)

Her remarks are likely to resonate with crucial constituencies in the renewable energy and liberal ranks, people active in both groups told Politico this week. Supporters hope Clinton will call for renewing an expired tax credit for wind energy producers as well as measures to curb global warming emissions.

“She’s going to talk about how [clean energy] remains a potential area of economic growth, and it’s increasingly one where we have global competition,” Neera Tanden, the policy director of Clinton’s 2008 presidential campaign and head of the Center for American Progress, a progressive think tank, told MSNBC.

The former top diplomat is unlikely, however, to touch the red-hot subject of the Keystone XL pipeline, which would ship Canadian tar sands crude oil to U.S. Gulf Coast refineries. Clinton’s State Department oversaw part of the environmental review process, which is still in progress, though President Barack Obama will have the final word on whether it gets built. MSNBC noted that Clinton has largely dodged questions about the pipeline, saying any answers could interfere with the process.

Christie, by contrast, pounced on Keystone XL during a Wednesday policy speech in Mexico City. He said delays on the pipeline have had “a chilling effect on economic growth and job creation. … We are missing an enormous opportunity when we delay development of the Keystone XL Pipeline,” he told a crowd at the American Chamber of Commerce of Mexico, a business advocacy group.

TransCanada Corp. (NYSE:TRP) first proposed the pipeline in 2008, during the Bush administration, but a final verdict seems unlikely to come before 2015. Obama postponed his decision on the pipeline until a legal dispute in the Nebraska Supreme Court is resolved, but the court isn’t expected to issue a final ruling before the new year.

Christie asserted that, if built, the 1,179-mile conduit would “drive down the price of oil and help consumers in all North American countries,” although the pipeline’s impact on global oil markets is highly disputed.

He also called for an end to the four-decade-long ban on U.S. crude oil exports - - a policy shift that the chief executive of Royal Dutch Shell PLC (NYSE:RDS.A), Ben van Beurden, called for earlier this week at a New York energy conference, the New York Times noted. Van Beurden said lifting the ban, which was meant to conserve domestic oil reserves after the Arab oil embargoes of the 1970s, could “make the global energy system much more stable.”

Clinton and Christie’s pre-presidential travels will overlap again on Friday, when Clinton arrives in Mexico to attend a charity event hosted by Mexican telecom magnate Carlos Slim, the world’s second-richest man. Clinton will be a speaker at the event, which also features Facebook Inc. (NASDAQ:FB)’s chief executive Mark Zuckerberg and soccer star Ronaldinho, Bloomberg News noted.