Updated Oct. 13, 12 p.m. | There may be plenty of good reasons why Republicans are now seeking a “fresh face” as House speaker. But picking from outside the existing chain of command would also create some big challenges.

It also would be highly unusual. It’s been nearly a century since someone was chosen to preside over the House without ever occupying a lower rung in the leadership. The past 16 speakers, in other words, have won with serious insider credentials — even when political common sense has pointed to the selection of a certified outsider.

It’s very possible that precedent will be broken this fall. Most of the members now in the roiling mix for speaker have made their reputations as policy experts, ideological warriors or marketing experts for the GOP — but have never been called on to practice those talents using the special tool kit of political power, staff resources and outside influence that comes along with a seat at the top table.

This is most noticeably true for Paul D. Ryan, who appears to have the speakership for the asking. (He’s spending the recess week back home in Wisconsin, deciding whether to abandon his long-standing disinterest in the job.)

He has been the face of the congressional GOP’s fiscal policy all this decade, first as chairman of the Budget Committee and now in the center chair at the Ways and Means Committee.

His credentials as a numbers and legislation wonk with an unusually deft touch as a policy salesman may be nonpareil at the Capitol. And his turn as the party’s last candidate for vice president has helped convince both his mainstream conservative and combative conservative colleagues he’s their best available option to become a unifying force.

But, after almost 17 years in office, Ryan has demurred time and again when urged to run for either speaker or any of the seven leadership posts filled by the votes of the House GOP.

None of those down-ballot partisan positions comes close to the speakership in terms of constitutional prominence (second in the line of presidential succession), institutional responsibility (chief steward of the legislative branch’s prerogatives and ethics), policymaking authority (principal author of the House’s legislative agenda) or party political clout (top internal disciplinarian as well as favor granter).

But each of the positions — from majority (or minority) leader down to Republican Conference secretary — can be a proving ground for those with aspirations for the top spot. The job descriptions all include, to varying degrees, the metaphorical care and feeding of the egos, anxieties, aspirations and campaign coffers of the rank and file.

Additional staff members are provided to help with different aspects of this work. But ultimately the members with these assignments have to hone specialized skill sets that have little to do with thinking big policy thoughts and then selling them.

Ryan has proven experience in drafting provocative budgetary blueprints, a zeal for shaping innovative tax simplification plans and a solid record as a party fundraiser to go along with all his perceived potential to heal the GOP’s profound internal injuries.

But that seemingly almost impossible task won’t be made an easier by the one gap in his résumé that his allies are portraying among his virtues: He has no real experience running the House or attending to the day-to-day needs of his colleagues.

He’s never done the floor leader’s work of managing the legislative calendar or the whip’s job of counting and corralling votes. He’s never been charged with the overall messaging, policy development, campaign strategy and internal GOP organizational tasks that are the purview of the other leaders.

Maybe most notably of all, he’s never gotten his hands dirty in what’s euphemistically dubbed “member services” — the catchall work of mediating petty turf wars, granting oddball VIP favors, providing late-night sustenance, refereeing travel requests, finding extra office space, bird-dogging personal behavior and intervening to prevent ethical transgressions.

Most of those high-risk and concertedly below-the-radar thankless tasks get performed by the floor leaders and whips, which helps explain why all but one speaker since World War II was previously in one or both jobs for at least a combined five years. And the exception, Republican J. Dennis Hastert of Illinois, was a serious practitioner of the member services dark arts as the appointed chief deputy whip for four years

Majority Leader Kevin McCarthy of California, who shocked the system by abandoning the speaker’s race, joined the elected leadership as whip in 2011. Steve Scalise of Louisiana, the whip for the past year, is among those pushing Ryan to run in part because he himself may be unelectable to the top job — not only because of past questionable contacts with race groups, but also because of his affiliation with the team of McCarthy and outgoing Speaker John A. Boehner, R-Ohio.

For now, none of the five others in the elected GOP hierarchy is seen among the likelier alternatives if Ryan does not budge from his current demurrals, although there is some talk about settling for some sort of “interim” speakership by either Cathy McMorris Rodgers of Washington, the conference chairwoman, or Greg Walden of Oregon, head of the caucus’ campaign organization.

A couple of others getting some mention have experience in the world of member services from past turns in the elected leadership. Pete Sessions of Texas and Tom Cole of Oklahoma are among Walden’s predecessors at the helm of the National Republican Congressional Committee, and Jeb Hensarling of Texas is the previous chairman of the Republican Conference.

Before the surprise election of Hastert, the last time a person was chosen speaker without a prior elected leadership post was 1919. The GOP had won back the House the previous fall after an eight-year hiatus, but the newcomer majority-makers had no interest in elevating an elder associated with the autocratic ways of their previous leader, Speaker Joe Cannon of Illinois. Instead, they rallied behind Frederick Huntington Gillett of Massachusetts, a respected 13-term veteran who’d never risen higher than chairmanship of a civil service oversight panel.

Gillett held the job for six years, through two different waves of factionalized dissent, before concluding in 1924 that his job security in the House was imperiled and successfully running for the Senate instead.

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