JUNEAU, Alaska — While every online swipe from former Gov. Sarah Palin still draws national attention and stirs fresh speculation about her political ambitions, back home she is no longer quite so imposing.

Even as she casts herself as an energy expert and is quick to attack the Obama administration on oil and gas issues, the two most prominent energy policies she put in place as governor of Alaska face new challenges less than two years after she left office.

Gov. Sean Parnell, Ms. Palin’s fellow Republican and former lieutenant, has announced that it is his top priority to undo parts of major oil tax increases that Ms. Palin made law. He argues that high state taxes, not just federal regulations, are preventing oil companies from exploring new drilling in Alaska and therefore jeopardizing future state revenues.

“Lower taxes means more competitive,” Mr. Parnell said last week. “It means more jobs.”

And the project Ms. Palin once portrayed as her principal legislative triumph, a plan to build a 1,700-mile natural gas pipeline that she said would transform the economy of Alaska and contribute to America’s domestic energy supply, seems an increasingly distant dream, undercut by low gas prices and more practical projects in other states.