U.S. President Barack Obama expressed confidence on Tuesday his economic reforms would work as senior officials began lobbying Congress to support the administration's jaw-dropping budget proposal.

"We need economic growth and access to credit. That is what we are focused on in the next year or two," White House Budget Director Peter Orszag told the House of Representatives Budget Committee, formally launching the sales pitch for the $3.5 trillion spending plan for the 2010 fiscal year.

Orszag and Treasury Secretary Timothy Geithner defended the budget, which envisions a whopping $1.2 trillion deficit and proposes increasing taxes on the wealthiest Americans to help pay for domestic initiatives.

President Obama marked the Interior Department's 160th anniversary today with an enthusiastically received visit to announce he was restoring the role of federal biologists in endangered species decisions.

"Today I've signed a memorandum that will help restore the scientific process to its rightful place at the heart of the Endangered Species Act, a process undermined by past administrations," Obama said to applause. "The work of scientists and experts in my administration -- including right here in the Interior Department -- will be respected."

President Barack Obama on Tuesday directed U.S. government agencies to consult with scientists before taking action that could harm endangered species, rolling back last-minute rules put forward by former President George W. Bush.

Obama, a Democrat who has spent much of his first six weeks in office undoing policies of his Republican predecessor, signed a memo urging agencies such as the Department of Transportation to consult with government scientists before pursuing projects that could hurt threatened animals.