The presumptive next speaker of the U.S. House of Representatives, Paul Ryan, is a onetime “young gun” of the Republican Party ― a conservative with a wonkish reputation who is clearly driven by higher political ambition.

Paul Ryan was nominated by his Republican colleagues Wednesday to lead the fractious House through the end of the Barack Obama presidency and potentially beyond.

It is the most important job in Congress and one that places him second in line to the presidency, after the vice president, should the commander-in-chief be impeached or otherwise vacate the Oval Office.

With the youthful father of three, the Republicans have chosen a telegenic 45-year-old spokesman who, while he occasionally comes off as bookish and cocky, is an ideologue influenced by neoclassical thinkers and repelled by the excesses of modern federal government.

Among his primary congressional passions: a determination to slash spending and eliminate the deficit.

“The fight we are in here ― make no mistake about it ― is a fight of individualism versus collectivism,” Ryan said in a 2005 speech to devotees of laissez-faire capitalist philosopher Ayn Rand, according to The New Yorker.

The radicalism of Ryan’s proposals have at times alarmed even those within his party, notably his call for the privatization of the Social Security pension system and Medicare public health service for seniors ― both American sacred cows for more than half a century.

But over more than a decade in Congress, Ryan has gradually earned a reputation of “Mr. Budget” among his Republican colleagues ― or “Mr. Austerity,” according to Democrats.

He was the lawmaker with sufficient potential for Mitt Romney to choose him to be his running mate in the 2012 White House race, stressing at the time that “with energy and vision, Paul Ryan has become an intellectual leader of the Republican Party.”

Paul Davis Ryan was born on Jan. 29, 1970 in the small town of Janesville, in the midwestern state of Wisconsin, where his Irish-Catholic family has lived for five generations.

He still lives in the neighborhood where he grew up and returns from Washington every weekend to his wife Janna and their three young children.

In high school he became president of his class, winning his first-ever election.

In 1988 he headed to Miami University of Ohio, where he nurtured his passion for economic theory and politics. When he volunteered for a congressional campaign as a student, it was ironically for Ohio’s John Boehner ― the man he will replace as House Speaker.

From 1992 to 1997, Ryan worked for a Republican senator in Washington and for Empower America, the organization founded by the influential conservative Jack Kemp, who took the young Ryan under his wing.

Ryan returned to Wisconsin, where he easily won election to the U.S. House in 1998 at the ripe age of 28.

Now in his ninth term, Ryan quickly earned a reputation in conservative circles.

He was thrust into the national spotlight when Romney put him on the ticket in 2012. He was chairman of the House Budget Committee at the time and gave the official response to Obama’s State of the Union address in early 2011, just after Republicans seized control of the House.

Ryan is a fitness fanatic, known for his adherence to the demanding P90X workout regimen. His physique became a media fixation, particularly while he was on the campaign trail with Romney.

The congressman has confessed to simple pleasures. His family comes first, but he also cherishes a youthful passion for hunting.

He has introduced his daughter to the sport, and bought her first Remington rifle for Christmas in 2011 when she was 10.

On the question of hot-button political issues like abortion or gay marriage, Ryan adheres to conservative orthodoxy and is opposed.

His primary challenge in helming the tumultuous Republicans through the November 2016 election and beyond will be transforming from an ideas man to a man of action in order to reconcile the two wings of the Republican Party ― the establishment moderates and the Tea Party hardliners.

Ryan had hesitated about running for speaker, and how the pitfalls of the mission could taint his politically pure reputation. (AFP)