Cruz sworn in as Texas' first Hispanic US senator

With Democrats controlling the Senate and Barack Obama as president, "we know to a metaphysical certainly that that bill is not going to pass," Cruz said on a media conference call shortly after taking office as the first Hispanic to represent Texas in the Senate.

But Cruz promised on the campaign trail to propose the repeal and said he'd keep his word. And if an abundance of tilting at legislative windmills is in Cruz's future, keep in mind that he was the longest of long shots to make it even this far.

The former state solicitor general and the son of a Cuban immigrant, Cruz was a virtual unknown when he announced his candidacy, but rode a groundswell of support from grassroots conservatives to shock powerful Lt. Gov. David Dewhurst in the Republican senatorial primary before cruising to victory in November.

Cruz swore the oath of office on a Bible he said his father Rafael used to read to him when he was a boy. He later stood on the Senate floor and watched his 4-year-old daughter Caroline wave down at him form a visitors gallery.

"The entire day has been magical," Cruz said. "I have to admit, any time someone addresses me as 'Senator,' I turn my head, trying to figure out who on earth they are talking to."

But Cruz also said he didn't plan to sit back quietly while he learns the lay of the land.

He not only lambasted federal health care reform but also the deal to avoid the fiscal cliff reached this week by the White House and Congress and supporters of stricter gun-control laws in the wake of the mass shooting in Newtown, Conn.

Cruz had yet to take office and couldn't vote on the fiscal cliff deal, which passed 89-8 in the Senate with the support of Texas' senior senator, John Cornyn, as well the woman Cruz is replacing, Republican U.S. Sen. Kay Bailey Hutchison. Cruz said he would have opposed it.