With an actress, an opera singer and a former NFL-linebacker jockeying for Congress, it’s again apparent that there’s no professional barrier to mounting a congressional, or even a Senate, campaign.

But the best candidates are really the ones with the best personalities.

Indeed, the desire to seek federal office often attracts a certain kind of person. As Democratic former Indiana Sen. Evan Bayh recently told CQ Roll Call, “Not too many people get elected to the U.S. Senate if you suffer from low esteem.”

Some professions are well enough represented in Congress to begin their own professional associations on Capitol Hill (see the GOP doctor’s caucus, for example). And there’s no shortage of lawyers, former state legislators and governors walking the hall of Congress.

But which professions make the best candidates?

It’s impossible to dissociate candidates from the districts and cycles in which they run, but here — in no particular order — is CQ Roll Call’s list of professions most recruited to run for Congress, based on conversations with campaign operatives from both sides of the aisle.

1. Lawyers: At least 21 members of the freshman class of 2014 are lawyers. Besides their knowledge of the law and persuasive speaking faculties, lawyers can make good candidates, especially if they have ties to people who can help them raise money.

On the other hand, trial lawyers are often tied to shady characters they may have defended. For instance, some Democrats who have rallied behind Maine 2nd District candidate Emily Cain are wary of fellow Democrat Joe Baldacci because of the clients he’s represented in court.

2. State legislators and elected officials: Legislators on the state level have a natural affinity for congressional service. “They get the process,” said one GOP campaign operative. The downside of that experience, however, is having a voting record that can be used against them.

But even more important, they have campaign experience. ‘They tend to know what they’re getting into,” said a Democratic operative. “It’s not a surprise — they know how busy they will be.”

What they likely haven’t done before is raise the kind of money it now requires to run for the House, let alone the Senate. One obvious exception is North Carolina, where Democratic former Sen. Kay Hagan of North Carolina was able to make the jump from the state Senate directly to the U.S. Senate, and where several state legislators are now considering challenges to Sen. Richard M. Burr.

When it comes to recruiting for the Senate, a state’s Congressional delegation is often the first place to look. But one Democrat cautioned that current politicians are sometimes “less willing to put together a diverse team” and prefer to surround themselves with staff who will “ingratiate themselves with the candidate.”

This cycle, former members Pete Gallego, D-Texas, Brad Schneider, D-Ill., and Carol Shea-Porter, D-N.H., are hoping to reclaim their old seats in the House. GOP former Florida Rep. Sandy Adams is hoping to return to Washington to represent a different district. And Democratic former Wisconsin Sen. Russ Feingold is running to retake the seat he represented for 18 years.

3. Political aides and operatives: At least 17 members of the current freshman class have worked as aides to federal elected officials or candidates. Rep. David Young, for example, was the chief of staff to Iowa Sen. Charles E. Grassley before mounting his own campaign. Virginia GOP Rep. Barbara Comstock worked as a congressional aide and presidential campaign aide before running for the seat long held by her old boss, former Rep. Frank R. Wolf.

Earlier this year, Indiana Republican Eric Holcomb left his job as a top aide to retiring Sen. Dan Coats to mount a bid for his seat.

Congressional aides, and their sometimes more politically savvy operatives on the campaign trail, know what it takes to run a campaign. But as campaign sources repeated Monday, it comes down to personality. Do the behind-the-scenes operators have the charisma to stand in front of the curtain? And can they tolerate other people telling them what to do? Not always.

There’s also the liabilities of a previous boss. In Tennessee’s deeply red 4th District, where Grant Starrett is challenging Rep. Scott DesJarlais to see who’s the most conservative, DesJarlais supporters are questioning Starrett’s work for former GOP presidential nominee Mitt Romney.

4. “Small” business owners: Everyone loves a small-business owner, and there are at least 38 members of the freshman class with a business background. But as one Republican operative admitted, it’s not clear how many of the businesses owned by current members are actually “small” given that it takes so much money to run for Congress.

“Obviously in the Republican party right now, we have a very anti-Washington mood,” added Brian Walsh, a longtime GOP strategist. A business experience boosts outsider authenticity, but as Walsh cautioned, it doesn’t always come with the political acumen needed to run and win a campaign.

5. CEOs and executives: These are the business leaders with money and the ability raise money. GOP Rep. Bruce Poliquin, a freshman on the House Financial Services Committee, came to mind for one GOP campaign operative as an example of a member who had a lucrative career before running for Congress and Wall Street connections.

Republicans tend to run more business owners than Democrats, one Democratic operative acknowledged. But Democrats see the allure, too.

“You want someone who can put in the time and financial means (to not work) and spend 40 hours a week raising money,” said a Democratic campaign operative. The alternative, he added, is to be independently wealthy.

Wisconsin GOP Sen. Ron Johnson self-funded his 2010 campaign to the tune of $9 million, but he’s vowed not to do that again in his rematch with Feingold. That means asking for money.

“For CEOs, it can be a humbling experience to be a candidate,” Walsh said. “It’s not glamorous sitting in a call suite.”

6. Military and law-enforcement veterans: A military background lends a candidate a similar kind of outsider credibility that Walsh said the GOP has been craving.

But veterans are popular on both sides of the aisle. Iraq war veteran Jim Mowrer, who challenged Rep. Steve King as a Democrat in Iowa’s 4th District last cycle, is mounting another campaign — this time against Young in the 3rd District.

A veteran is almost guaranteed to have a compelling story. “There’s no downside to running as a vet,” one Democrat said. “But running as a veteran doesn’t mean you’re going to win.” Heroism doesn’t guarantee fundraising prowess.

And though they make disciplined campaigners, veterans “don’t always have the best outgoing personality” when meeting voters, a Republican noted.

7. Clergy: While veterans may have difficulty connecting with voters on a personal level, religious leaders who can go into “pastor mode” do a good job of engaging with their audience, a Republican campaign operative said. There are three members of the 2014 freshman class with clergy backgrounds.

8. Doctors: Doctors almost fall into the same category as business owners, Walsh said: They’re viewed as community leaders with some legitimacy outside Washington. That’s why Michigan Rep. Dan Benishek goes by “Dr. Dan,” while DesJarlais, “a small family doctor” promises “the right prescription” on his campaign website.

9. Celebrities: Besides the obvious benefits of name recognition, celebrity status often means wealth, or at the very least, it confers the ability to fundraise.

This year, actress Melissa Gilbert, the star of “The Little House on the Prairie” TV series, is running for Congress as a Democrat in Michigan.

But fame doesn’t always breed political success. In Illinois, for example, state Sen. Napoleon Harris, an ex-NFL linebacker, is considering a run for the Democratic nomination to challenge Sen. Mark S. Kirk. Unfortunately for him, there’s a more experienced candidate in the race.

10. Academics: The biggest political upset of 2014 came from an economics professor unseating the House majority leader. Virginia Rep. Dave Brat joined a group of professors in Congress, who told CQ Roll Call intern Ivan Levingston earlier this summer that their higher education experience prepared them well for higher office.

Related:

Roll Call Race Ratings Map: Ratings for Every House and Senate Race in 2016

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