WASHINGTON — Several large Houston-area companies in the Republican-leaning energy industry and other sectors have been shifting federal campaign contributions to Democrats, who are flexing their new power in Congress as they draft legislation on energy and the environment.

Political action committees for companies including ConocoPhillips, BP Corp. and Continental Airlines gave a significantly higher percentage of their contributions to Democrats in the first quarter of 2007 than they did for the November 2006 election, when Republicans lost their majorities in the House and Senate.

Corporate officials warned that first quarter contributions in a two-year election cycle should not be interpreted as an indication of a major change in long-term giving strategy. And some business PACs, including that of energy giant ExxonMobil, are still contributing largely to Republican lawmakers and candidates.