Washington  - US President Barack Obama and key administration officials launched a full media blitz Wednesday to push for limits to climate-damaging pollution in the United States, coinciding with Earth Day.

Obama touted the importance of wind power during a trip to the US state of Iowa and called for a "new era of energy exploration," sounding a theme repeated by a series of cabinet members who testified before Congress on the same day.

"On this Earth Day, we must state in no uncertain terms that we have a responsibility to curb the carbon emissions from fossil fuels that have begun to change our climate," Energy Secretary Steven Chu told the Energy and Commerce Committee of the House of Representatives.

The House committee planned to hear from dozens of government, environmental and business officials during four days of hearings this week as it considers legislation that would force US companies to pay for emissions that cause global warming.

The legislation has struggled to gain traction in Congress amid opposition from conservative lawmakers and some Democrats from coal- producing states, who fear a cap on greenhouse gas emissions will do undue harm to the US economy.

Chu testified before the House committee Wednesday together with Transportation Secretary Ray LaHood and Environmental Protection Agency head Lisa Jackson. Former vice president Al Gore, who won the Nobel Peace Prize in 2007 for his efforts to raise awareness on climate change, is set to appear on Friday. (dpa)