WASHINGTON (Reuters) - For new U.S. senators, the drill typically goes something like this: Keep quiet once you arrive in Washington, learn how things work and then begin asserting yourself.
That is not exactly the path Ted Cruz is taking.
He has been in office for barely six weeks, but already the senator from Texas, a favorite of the conservative Tea Party movement, has shown a provocative, in-your-face style that has won him criticism and praise.
Cruz, 42, has been chided by Democrats and even fellow Republicans who say he trampled Senate etiquette during contentious hearings in which he went after former Republican Senator Chuck Hagel, Democratic President Barack Obama's nominee for defense secretary.
While some Republican leaders have sought to broaden the party's appeal with a more moderate tone on a range of issues, Cruz has unabashedly - and often dramatically - cast himself as a hard-line conservative with a distaste for compromise.
He was one of only three senators to vote against Secretary of State John Kerry's confirmation, and sponsored a doomed-to-fail bill to repeal Obama's healthcare overhaul, which some conservatives view as socialized medicine.
Cruz voted against both a Hurricane Sandy relief package and raising the government's debt ceiling. Cruz, the son of a Cuban immigrant, has also expressed "deep concerns" about a bipartisan Senate plan to give many of the nation's 11 million illegal immigrants a possible path to U.S. citizenship.
All of which have made Cruz an intriguing player in Washington at a time when some Republicans are emphasizing social programs and compassionate immigration policies to try to win over Hispanics, who voted overwhelmingly for Obama in the November election.
Cruz's early influence in Washington was evident on Tuesday, when a Senate committee hearing on Hagel's nomination as defense secretary essentially became a discussion of Cruz's tactics.
In recent weeks, Cruz has suggested that Hagel's nomination was endorsed by Iran, and that Hagel was not being forthcoming enough about his finances.
Before the Democratic-led Senate Armed Services Committee voted to back Hagel's confirmation on Tuesday on a party-line, 14-11 vote, Cruz angered lawmakers in both parties by suggesting, without giving evidence, that Hagel might have taken money from countries such as North Korea.
That drew a rebuke from Democratic Senator Bill Nelson of Florida, who said Cruz had "gone over the line."
It also prompted a warning to Cruz from a fellow Republican, John McCain of Arizona, who had sharply questioned Hagel during the hearings and was about to vote against Hagel's nomination.
"No one on this committee at any time should impugn his character or his integrity," McCain said of Hagel, a fellow veteran of the Vietnam War.
'A POLITICAL PHENOMENON'
Cruz's aggressive approach has made him a favorite conversation piece in Washington, where headlines in recent days have referred to him as an "attack dog" and a "chicken hawk" - a term used by critics for those who take a strong pro-defense stance but have served little or no time in the armed forces.
CNN broadcaster Wolf Blitzer chided Cruz during an interview about the need to compromise. MSNBC host Joe Scarborough, a former Republican congressman from Florida, refused to utter Cruz's name while denouncing the senator's questioning of Hagel at his confirmation hearing as a "clown show."
Cruz, who declined through an aide to be interviewed for this story, has been unapologetic.
"I view all of that as a sign that maybe we're doing something right," he said recently on conservative Glenn Beck's radio show.
Cruz's ambition and no-holds-barred style have made him a hero among conservative activists and raised talk that Cruz - like Florida Senator Marco Rubio, another Hispanic rising star among Republicans - might run for president as soon as 2016.
"He's a political phenomenon, and he has managed to become a national figure in a very short period of time," said Steve Munisteri, chairman of the Texas Republican Party. "I have no doubt that a year from now, virtually every Republican activist in the country will know who Ted Cruz is."
But some analysts said Cruz's confrontational approach also put him at risk of being marginalized and portrayed as a political bomb thrower in a gridlocked Congress.
"He talks about issues from an ideological perspective. But has shown no sign of being someone who could sit down and work out a solution to a complicated problem," said political scientist Cal Jillson of Southern Methodist University in Dallas.
Norm Ornstein, a congressional analyst at the American Enterprise Institute, said Cruz had been pushing the limits on standards of behavior in the tradition-bound Senate.
"In the modern, cable television-talk radio media age, the more outrageous you are, the more attention you get," Ornstein said. "And Cruz is no dummy. He's a smart, articulate guy. You'll be seeing and hearing him a lot."
Cruz captured his Senate seat after upsetting Texas Lieutenant Governor David Dewhurst, the choice of the state party establishment, in the Republican primary. That followed months of political spade work at small county meetings around the state that won Cruz a dedicated grass-roots following.
"I see Ted as someone who gives a voice and representation to people like me, who feel like they have had no voice and no power," said Katrina Pierson, founder of the Grassroots Texans Network and a board member of the Dallas Tea Party, who was an early Cruz supporter.
But Cruz, a Harvard Law School graduate who was a clerk for former Supreme Court Chief Justice William Rehnquist and served as Texas solicitor general, has also built bridges with more established Republicans eager to court the party's conservative wing and promote a rising Hispanic star.
Party leaders gave him a plum speaking slot at last year's national convention, and sought-after appointments to the Senate Judiciary and Armed Services committees once he was elected. They also made him vice chairman of the Senate Republican campaign arm, which will recruit and back candidates in the 2014 elections.
The top two Senate Republicans, Mitch McConnell of Kentucky and John Cornyn of Texas, both hope to avoid primary challenges from conservatives next year and have sought to strengthen their relationships with Cruz.
Cruz accompanied McConnell on a congressional visit to Israel and Afghanistan last month and won an admirer in the process. McConnell told the National Review Online afterward that Cruz was "ready for prime time on day one, which is pretty unusual for somebody who just got sworn in."
Republican leaders also have been eager for Cruz, whose father was born in Cuba and came to Texas in 1957, to help them gain support among Hispanics.
But Cruz refused to back a bipartisan Senate immigration plan, putting him at odds with Rubio and with the views of most Hispanics, who polls show support a broad path to citizenship.
"To allow those who came here illegally to be placed on such a path is both inconsistent with the rule of law and profoundly unfair to the millions of legal immigrants who waited years, if not decades, to come to America legally," Cruz said in a statement after the Senate immigration plan was made public.
Trey Martinez Fischer, a Democratic state representative in Texas and head of the state's Mexican-American Legislative Caucus said Cruz represented the "extreme conservative, highly partisan" wing of the Republican Party.
"I would caution anybody who looks to Senator Cruz as a role model for Hispanics," Martinez Fischer said. "There is a difference between being the Hispanic candidate and being the candidate who happens to be Hispanic. He's the latter."