The migration of Capitol Hill staffers to the campaign trail has slowly begun as the season of summer politicking ramps up.

But compared with 2008, when both parties had wide-open presidential fields and Hill staffers flocked to a host of candidates, this year’s slower campaign pace has not prompted the same kind of early exodus.

“The campaigns are being more strategic,” one Republican campaign source observed. “At this point four years ago, the campaigns were hiring and hiring. This year, they are getting key folks and keeping costs down.”

So far, the staff shuffles are heavier on the Republican side, where several candidates are vying for the nomination to challenge President Barack Obama in 2012.

The Republican National Committee recently plucked Ryan Tronovitch, deputy communications director for freshman Sen. Rob Portman (Ohio), to be a regional press secretary. Joe Pounder left his post as communications director to freshman Sen. Marco Rubio (Fla.) in May to join the RNC as research director and deputy communications director for the 2012 cycle. No stranger to presidential politics, Pounder worked on former Massachusetts Gov. Mitt Romney’s 2008 campaign and later joined the camp of Sen. John McCain (Ariz.).

Romney’s campaign has also plucked a few Hill veterans. Webber Steinhoff, a Massachusetts native, left his post as communications adviser to Senate Minority Leader Mitch McConnell (R-Ky.) in May to head north as director of rapid response for Romney. Communications Director Gail Gitcho took off from the office of Sen. Scott Brown (R-Mass.) in April to hold the same title for Romney.

A couple of House-side staffers have also moved to campaigns: Kris Anderson, who worked as the director of strategic communications for Majority Whip Kevin McCarthy (Calif.), was an early hire for Jon Huntsman, the former Utah governor who announced his presidential candidacy last week. Anderson is now Huntsman’s research director.

Rep. Michele Bachmann (Minn.) formally announced her presidential bid Monday, a move that had been anticipated — especially when she moved her chief of staff, Andy Parrish, out of her Congressional office and into a political role earlier this month.

Scores of aides left the Hill in 2008 when Obama, McCain and then-Sen. Hillary Rodham Clinton (D-N.Y.) ran for president. This year, Bachmann and Rep. Ron Paul (R-Texas) are the only sitting Members currently running.

Fewer Democratic staffers have moved to the campaign trail so far this year. Peter Bondi, formerly with the Senate Banking Committee, recently moved to Chicago to serve as deputy research director for the Obama campaign.

Stephen Krupin, speechwriter for Senate Majority Leader Harry Reid (D-Nev.), is moving out soon to serve as the Obama campaign’s director of speechwriting. In that role, Krupin, a Washington native, will coordinate speech for campaign surrogates while the White House speechwriting team continues to pen speeches for Obama.

Obama’s campaign hasn’t snatched many Hill staffers so far this year, but several former administration officials — many of them also former Congressional aides — have made the move to Chicago for the re-election. Campaign manager Jim Messina served as Obama’s deputy chief of staff in the White House and before that was a longtime aide to Sen. Max Baucus (D-Mont.).

David Axelrod left his role as senior adviser in the White House in January to return to Chicago, where he is focusing on Obama’s re-election campaign.

And after leaving his position as assistant press secretary in the White House to serve as communications director for former White House Chief of Staff Rahm Emanuel’s successful mayoral campaign in Chicago, Ben LaBolt shifted over to Obama’s re-election office, where he now serves as press secretary. LaBolt worked as Obama’s press secretary when he served in the Senate, and like so many staffers in the 2008 election cycle, he left the Hill to be deputy press secretary for the Illinois Democrat’s first presidential campaign.