Gregg is opposed to Obama's first major piece of legislation.

WASHINGTON (CNN) – Republican Sen. Judd Gregg is putting a final exclamation point on his withdrawal as Barack Obama’s designee for Commerce Secretary with a promise to vote against the president’s economic stimulus package.

Gregg’s office confirmed the decision Friday.

The New Hampshire senator cited the stimulus package as a primary reason for backing out of the job offer, calling the bill and potential changes to Census oversight “irresolvable conflicts for me.”

“We are functioning from a different set of views on many critical items of policy,” Gregg said in a statement Thursday.

The House approved the stimulus plan Friday afternoon, and a Senate vote is expected later in the day. Two weeks ago, Gregg voted against the Senate version of the bill.