Rand Paul pledged on Thursday to use his Senate campaign to strengthen the Republican Party by promoting “small government principles,” one day after he officially entered the race for Kentucky’s open seat.

In a press conference at the Kentucky Republican Party headquarters in Louisville, Paul, the son of Rep. Ron Paul, R-Texas, praised the “tea party” movement and said that “career politicians” had sold taxpayers “down the river.”

“We, the members of the Tea Party movement, you, the members of this movement, have come to take our government back from the special interests, from the lobbyists, from the pork barrel politicians who continue to spend our country into oblivion,” he said, according to a transcript of his statement posted on his campaign Web site.

Over the past few months Paul, an eye surgeon, has mounted a campaign that could pose a serious threat to Secretary of State Trey Grayson, the GOP establishment’s favored candidate for the nomination.