Katie McGinty, who last month won a tough race to become the Democratic nominee for a U.S. Senate seat from Pennsylvania, has changed her campaign manager.

McGinty this week brought on Jordan Marks, a longtime political hand who has ties to former Gov. Ed Rendell, McGinty's campaign chairman.

Marks worked in Rendell's gubernatorial administration and on his 2006 reelection campaign, was on Hillary Clinton's 2008 team in Pennsylvania, and worked for national Democrats' congressional campaign operation.

Most recently, Marks, 37, helped the Democratic women's group EMILY's List in a Senate primary in Maryland. EMILY's List is a key McGinty backer.

McGinty's campaign said the change was part of an effort to expand for the general election. Her former campaign manager, Mike Mikus, will work on long-term strategy, a spokeswoman said.

"We are very excited that we are bringing on more capacity. Mike will continue to work with the campaign and serve as the chief strategist, and Jordan will serve as campaign manager," spokeswoman Sabrina Singh said.

The change, which took place Monday, comes after McGinty beat Joe Sestak and two other rivals in the April 26 Democratic primary.

She scored a big win in the end, but had lagged for months and needed more than $4.5 million in outside spending help to prevail.

National Democrats were unimpressed with the campaign's early effort, according to one Washington source. McGinty struggled to gain traction for months and spent heavily. A spokeswoman for the Democrats' national Senate campaign arm, however, said McGinty's campaign had hit all the benchmarks required for the party endorsement.

The party's national arm has invested heavily in McGinty, hoping she can unseat Sen. Pat Toomey (R., Pa.) and help Democrats take control of the chamber. The race is expected to be one of the most hotly contested in the country.

jtamari@phillynews.com @JonathanTamari