Sen. Mike Crapo (R-Idaho), right, arrives at Alexandria District Court, where he pleaded guilty Friday to drunken driving. (Evan Vucci/Associated Press)

The office of Mike Crapo would like the three-term Republican senator to be known for his work on the powerful banking committee, for his participation as a member of the Gang of Eight on big-budget concerns and for his efforts to resolve a decades-old land management issue in Idaho’s Owyhee County.

Instead, Crapo (pronounced CRAY-poe) has entered the public’s consciousness as the Mormon senator who drank vodka tonics alone in his Capitol Hill apartment on the night of Dec. 22, climbed into a 1999 white Jeep and took a half-hour drive past the monuments and into Alexandria, where he ran a red light and then scored a 0.11 on a breath test. His arresting officer noted bloodshot eyes, slurred speech and an odor of alcohol.

On Friday morning, the 61-year-old Idahoan, wearing a gray suit with a powder-blue power tie, took a seat with a staffer and other traffic violation defendants at Alexandria District Court. Called before the judge, he pleaded guilty to drunken driving and received a suspended sentence of 180 days in jail, a $250 fine, a year’s suspension of his driver’s license and enrollment in an alcohol safety program. The hearing lasted 10 minutes.

Crapo’s real punishment will last much longer, and it is linked less to the severity of his transgression than the degree to which his crime clashed with the squeaky-clean image of Mormon politicians that Mitt Romney personified over the past year. (“I tasted a beer and tried a cigarette once as a wayward teenager and never did it again,” Romney told People magazine.) If Crapo has done himself lasting damage, it is most likely to be with Idaho voters, especially the quarter who are Mormon. They may question whether they know the man they have repeatedly elected, or whether the Potomac had poisoned their senator’s principles. “He held himself up to be a certain kind of guy: straight cut, Eagle Scout, family man, former Mormon Bishop,” said a Dec. 30 editorial in the Idaho State Journal. “Your reputation as a faithful Mormon conservative has been blown to smithereens.”

Crapo immediately tried to put such concerns to rest. “I have recently made personal choices that are at odds with who I am, who Idahoans rightly believe me to be and who I strive to be,” Crapo said Friday in front of more than a dozen reporters, cameramen and photographers in a courtyard outside the courthouse.

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In his long, blanket apology, he asked the forgiveness of voters, who he said justly held him to a higher standard. Then he got specific. “In recent months, and for less than a year, I have on occasion had alcoholic drinks in my apartment. It was a poor choice to use alcohol to relieve stress — and one at odds with my personally held religious beliefs.” He declined to elaborate on the source of the stress and added that he hopped into the car because he had been “restless and could not sleep.” (“I was alone during this drive and never left my vehicle,” he clarified.)

Unlike the lewd-conduct arrest of Crapo’s former Idaho colleague, Larry E. Craig, the ­drunken-driving incident is unlikely to have an impact on Crapo’s reputation in the Senate, a chamber that is not particularly judgmental about the consumption of alcoholic beverages.

“His colleagues will probably view him with a certain degree of sympathy,” said Jennifer Duffy, a Senate analyst at the Cook Political Report. “But this is not likely to impact his relationship with them in any negative way.”

Crapo had reached out to several Republican colleagues, who said they were surprised at his arrest but expressed their support.

“He is thoroughly hurt by his own actions and feels tremendously sad that he allowed this to happen,” said Sen. Orrin G. Hatch (Utah), a fellow Mormon and good friend. “Even his wife can’t understand why it happened.”

Hatch described Crapo as being under tremendous stress leading up to the incident, saying that “the man has more on his plate than most senators,” but he emphasized that Crapo “will make it right” and “I’ll be there for him.”

Crapo had been explicit about his teetotaling in the past. When he sponsored a bill to cut taxes on small beer brewers in 2010, he made a point of framing his measure as a support of businesses, not breweries, telling the Associated Press that he abstained from alcohol but would celebrate the bill’s passage with a root beer. On Friday, Crapo pointedly called himself a “lifelong member of the Church of Jesus Christ of Latter-day Saints, which is well known for its standards against consumption of alcohol.”

The Mormon ban on alcohol stems from Section 89 of Doctrine and Covenants, one of the faith’s holy scriptures. It documents the revelation, known as the “Word of Wisdom,” that the religion’s prophet Joseph Smith received in Kirtland, Ohio, on Feb. 27, 1833. (Church lore holds that Smith’s wife, Emma, had been complaining about the brethren’s smoking and drinking.) The revelation touts fruits and vegetables but reads that “inasmuch as any man drinketh wine or strong drink among you, behold it is not good” and that “tobacco is not for the body” and that “hot drinks are not for the body or belly.”

The ban has both theological and historical underpinnings. Mormons believe that God has a physical body, and thus the human body is not merely a vessel for the soul but a tabernacle to which it is forever bound. Professor Richard Bushman, a prominent Mormon historian, noted that the period during which Smith received his revelation coincided with temperance movements started in reaction to the era’s rampant alcohol abuse.

For the first 100 years after the revelation, there was a great debate in the Mormon world about whether the revelation was a hard ban or simply an endorsement of moderation and clean living. (Smith himself writes of sipping wine in his journals.) During this time, bishops were known to take kegs of beer out hunting, high church leaders chomped on cigars and faithful members sipped morning coffee, Bushman said. That ended in the 1930s, when the hard-liners won the debate and abstinence became requisite for church membership. (The suitability of imbibing caffeine in non-hot drinks, however, long remained a sticking point.)

The historical uncertainty about the ban doesn’t do Crapo much good. “It does not absolve Crapo of his transgressions because nowadays Mormons would be shocked,” Bushman said.

A spokesman for the Mormon church declined to comment on the Crapo incident.

In a nod to Mormon supporters, Crapo said Friday morning: “I will carry through on the appropriate measures for repentance.” That means Crapo will meet with his local bishop and work to attain forgiveness. The church can refer members to Alcoholics Anonymous meetings, but increasingly its own social services wing treats substance abuse with a more scriptural approach. For a time Crapo will probably be asked to refrain from taking the sacrament at church, and his Temple Recommend, a physical card that faithful Mormons must present to gain admission to the sacred temples, will probably be temporarily revoked. It is unlikely that Crapo will have to appear before a church court, which is reserved for more serious transgressions such as adultery.

The attention on Crapo’s arrest, in itself, validates the church’s success “at trademarking clean living as part of what it means to be Mormon,” said Patrick Mason, a professor of Mormon studies at Claremont Graduate University in California. “It speaks to the fact that people in America don’t know much about Mormons, but they do know a couple of things, and one is that Mormons don’t drink.”