During Congressman Joaquin Castro’s first two weeks in Washington D.C., he was hesitant to walk the halls of the Capitol Building by himself. It wasn’t so much that Castro felt intimidated being around some of the most recognizable faces in national politics, nor was he cowed at the prospect of having the same job as icons like Abraham Lincoln, John F. Kennedy and Henry Clay. No, Castro opted to always bring along members of his seasoned congressional staff as he strolled around the ornate and sometimes bewildering warren of committee rooms and passageways that make up the Capitol for a much more prosaic reason: “You don’t know where the bathroom is,” he says with a chuckle.

Pressing insider knowledge like that aside, in the course of a frenetic first eight months in office, Castro has settled into his new job in a way that few newly elected members of Congress ever have. In a city where attention often translates into power, Castro has already appeared on influential Sunday morning policy gabfests like NBC’s Meet the Press and This Week With George Stephanopoulos on ABC, and a University of Minnesota Smart Politics project study declared him the second-most talked about new representative (behind only Iraq war vet and double amputee Tammy Duckworth of Illinois), based on mentions in the media. More consequently, Castro was both elected co-president of the incoming class of Democratic House members and landed assignments on committees—Armed Services and Foreign Affairs—that usually go to congressional veterans. As debate over immigration reform has taken center stage nationally, Castro has become one of the most influential voices to argue in favor of addressing the nettlesome issue.

His lightning fast start is noteworthy for a host of reasons—not the least of which is what it could mean in terms of federal support for his San Antonio constituents. The manner in which Castro has quickly made a name for himself has also been noticed. “A lot of freshmen come in with high hopes of getting onto big committees and they learn you have to earn your way onto the better committees,” says Xavier Becerra, the veteran congressman from Los Angeles who chairs the House Democratic Caucus. Becerra credits Castro with coming into office and quickly learning the internal dynamics of how the institution functions—part of which means understanding when it’s best to stay mum. “To get elected, you have to be a good speaker. But if you think back, some of the best leaders we’ve had were good listeners and knew how to connect with people, and that is something he does well,” says Becerra, the highest ranking Latino in Congress. “Everyone is expecting great things, and I am no exception to that.”

All the talk about Joaquin Castro suddenly matching his twin brother Julián’s political potential—he’s already being spoken about as a challenger to Republican U.S. Sen. Ted Cruz—seems far from his mind during a phone interview from Washington. Instead, Castro sounds a lot like someone who is both thrilled with the possibilities to do the sorts of big things that being a congressman allows, while also still struggling to wrap his arms around a daunting job. The real work of getting up to speed on all that crosses a congressman’s desk is both an ongoing and ultimately fruitless task.

"You deal with so many subjects every day that it’s impossible to be a master of all of them,” says Castro. “But you should know something about them.” The former Texas state legislator and Stanford and Harvard Law graduate spends much of his time studying issues as disparate as immigration reform—a special focus of his, particularly given his own family’s well-known immigrant tale—and terrorism in North Africa. One of the ironies of being a congressman, at least if you’re being honest and doing the job right, is that you’re constantly seeking out people who know more than you do about particular issues. “I reach out to more senior congresspeople on specific issues and I make an effort to find people who are subject matter experts,” says Castro. “I also learned from my experience going into the Texas legislature, when I got in at age 28 and felt underprepared.”

The sheer breadth of the demands of Castro’s job is reflected in his daily schedule. Indeed, on a recent day the congressman had a slate of appointments that can only be categorized as punishing. Starting at 8 in the morning with a meeting with the director of the National Institutes of Health, Castro’s day includes everything from a House Foreign Affairs hearing on the humanitarian crisis in Syria to two different luncheons—one for the state’s Democratic congressional delegation and another to discuss immigration—to actual votes on the House floor, meetings with constituents and a reception for freshmen congressmen that doesn’t end until 8 in the evening.

While the demands on Castro’s time and attention are many—his schedule doesn’t begin to reflect the fundraising help he has provided to Democratic colleagues. He says he tries to always remember to focus on the interests of the voters who sent him to Washington. “If you allowed yourself, you could get consumed with routine things about Congress and the big national issues that overshadow everything,” he says. “I make a point with my staff to carve out time to focus on San Antonio.” For Castro, that has meant efforts both symbolic and substantive. For instance, the congressman used his influence on the House Armed Services Committee to include measures important to San Antonio in the National Defense Authorization Act, which the House passed in June. Included in the legislation was a mandate for the Defense Department to look closely at ways to trim costs overseas before asking to close bases at home, an important point for a place known as Military City, USA. The bill also requires an independent progress report on efforts to address the incidence of sexual assault in the military; Castro’s very first hearing on the Armed Services Committee reviewed sexual misconduct at Lackland Air Force Base and initiatives to prevent it.

Besides also pushing legislation to make secondary and higher education more available, Castro has done the meat-and-potatoes work of any political office holder: tending to individual constituent needs. That has meant helping people who are having difficulty accessing their Social Security or Veterans Affairs benefits. Castro has also handed out medals to area veterans, including in June when he presented a Purple Heart to Bexar County Sheriff Deputy John Lauer to honor the longtime law enforcement officer’s three tours of duty in Iraq, where he was severely injured.

As much as Castro has enjoyed plaudits for his individual entrée into Congress, he is also keenly aware that the institution itself is about as popular as a toothache. That takes some getting used to, he says. “It’s strange as a person to join a body or institution that is not popular because you don’t think of yourself as deserving unpopularity. It’s a mental adjustment,” he says. He’s also hopeful that the 70-plus new members of Congress can start to change that perception. In part, he says that is a matter of simply being more civil to those who disagree with him and cultivating personal relationships with Republicans in hopes that it will translate into a less toxic political atmosphere. Castro isn’t just paying lip service to the importance of the parties working together.

In July he was among 81 Democrats and Republicans—and the only one from Texas—to join a group of legislators called the No Labels Congressional Problem Solvers, a coalition dedicated to ending political gridlock.

Castro also understands that part of the solution to buffing the image of Congress is simply getting things done. “My biggest surprise is individually how busy I am during the days,” he says. “I look at my own individual quick pace and look at the output of Congress and it doesn’t match that pace. The output is not much.” Still, despite the grueling pace of the job—which he balances with visits home to San Antonio every weekend to see his fiancée Anna Flores (they got engaged in June) and his family—Castro is definitely not complaining.

“There are incredible responsibilities on a wide range of issues and we are dealing with subjects that make a difference in people’s lives,” he says. “Overall, it’s an incredible job.”