The good people at the Center for Responsive Politics and are at it again. After revealing that the majority of Congressmen and -women are millionaires, the disclosure site has compiled a list of the most popular Congressional investments from 2012. The list features the most common stocks owned by anyone who was in Congress for at least part of 2012, broken out across party lines. Today we're looking at the four energy stocks on the list.

1. ExxonMobil (XOM 1.26%)
No surprise here. Ranking eighth overall, Exxon is probably the first company that Americans think of when energy stocks come up. Fifty-five members of Congress owned shares of Exxon in 2012, with approximately twice as many Republicans as Democrats.

2. Chevron (CVX 0.53%)
At No. 17 on the overall list, Chevron isn't far behind its Big Oil peer. We've argued at The Motley Fool that Chevron is, in fact, a better investment over Exxon. Apparently Congress doesn't feel that way, as just 45 members disclosed a position in the oil giant.

3. Schlumberger (SLB 2.11%)
This one is a bit of a sleeper. Ranking 34th overall (tied with Vodafone and Citigroup), Schlumberger is a name many people have probably never even heard of. Yet the French oilfield-services company is the largest in the world, providing technology, project management, and data solutions to oil and gas producers. Twenty-seven members of Congress owned it in 2012, and it's the only energy stock on the list that is almost perfectly split down party lines.

4. ConocoPhillips (COP 1.51%)
Finally, we have ConocoPhillips, one of the largest independent oil and gas producers in the world. It's also one of the most important players in the current U.S. oil and gas boom, with efficient operations ranging from south Texas to Alaska. Twenty-one members of Congress disclosed shares in 2012, and again the breakdown by party featured twice as many Republicans as Democrats.

Bottom line
Energy is a hot-button issue in the U.S. right now, as we reconcile booming oil and gas production with concerns about the impact of fossil fuels, throwing in record numbers of wind and solar adoption for good measure. Because Congress is instrumental in developing and passing legislation that could directly affect these companies, we need to keep an eye on who owns what and who votes how. America's energy future shouldn't be tied to the success of a Congressperson's portfolio.