A former Secret Service agent has entered the uphill contest to unseat Sen. Ben Cardin (D-Md.) in 2012.

Daniel Bongino — whose spent four years with the New York Police Department and 12 years with the Secret Service, most recently at the Baltimore Field Office — is running as a Republican. He is the first GOP candidate to enter the contest against Cardin, who will be difficult to defeat in a heavily Democratic state with President Obama at the top of the ticket.

“I had a very promising career in the Secret Service. This isn’t a scheme,” Bongino said in an interview Wednesday, explaining that his willingness to sacrifice that job was an indication of how serious he was about this campaign.

Bongino added that while he couldn’t identify the exact moment he decided to jump into electoral politics, “I can certainly tell you I got the overwhelming feeling of being tired of being tired. It’s very difficult to sit on the sidelines anymore.”

In a statement announcing his candidacy, Bongino said: “In my career, I’ve seen the effects of failed policies on citizens in our inner cities. I’ve had the honor of traveling to 27 countries with the Secret Service. ... Whether we are talking about education, health care, social programs or tax structure, Americans are the most creative entrepreneurs in history. But they are being held back by our government.”

Bongino, 36, joined the Secret Service in 1999 as a special agent after four years with the NYPD, according to his campaign biography. He worked in the New York field office on investigations covering financial fraud and international terrorism, among other issues. Then he served as an instructor at the Secret Service Training Academy in Beltsville, Md., before joining the Presidential Protection Division in 2006. He served on the protective details of both Obama and President George W. Bush. Bongino transferred to the Baltimore office in 2010, and left the Secret Service last month to begin his campaign.

Bongino and his wife Paula, a web design consultant and small-business owner, live in Severna Park with their seven-year-old daughter.

Bongino‘s campaign will be chaired by former gubernatorial candidate Brian Murphy. Murphy, a business investor from Montgomery County, got 24 percent of the vote in the 2010 Republican primary against ex-Gov. Robert Ehrlich, who went on to lose to Gov. Martin O’Malley (D) in the general election. Murphy got some attention when he received an unexpected endorsement from Sarah Palin the month before the primary.

Murphy sent a message to his own supporters last week, saying Bongino’s “intellect, training, passion, life experiences, and principles are exactly what Maryland needs in the US Senate.”

Though Bongino is the only announced Republican candidate to take on Cardin, former Queen Anne’s County Commissioner Eric Wargotz is also mulling a run. Wargotz, a physician, ran against Sen. Barbara Mikulski (D) in 2010, losing to the incumbent by 26 points.

Wargotz spent $667,000 of his own money on the contest, and his ability to self-fund could help him against Bongino or any other Republican should he choose to enter the 2012 race. It is relatively easy to qualify for the ballot in Maryland, and 18 candidates ran for Senate in 2010.

Cardin will likely be a tough opponent for any Republican nominee. He won the seat in 2006 by 10 percentage points against then-Lt. Gov. Michael Steele (R), and his reelection bid will benefits from sharing the ballot with Obama, who won Maryland by 26 points in 2008.

But Bongino doesn’t buy that, saying that “real conservative ideas” will prove popular in the state.

“Maryland is not the blue state everybody thinks it is,” he said. “I know the voter registration numbers say otherwise but I’ve been out there.”