In an indication of how seriously Republicans are taking the Democratic challenge in a once-safe GOP district, party bigwigs are starting to head to Maryland’s 1st district to lend support to Republican nominee state Sen. Andy Harris, who is hoping to hold on to one of only two Republican House seats in the Old Line State.

Former Massachusetts Gov. Mitt Romney, who is rumored to be on the short list for a GOP vice presidential nod, will appear at a Harris fundraiser in Baltimore on Sept. 12.

“In this time of economic uncertainty, I am proud to have the support of such a successful business leader and governor,” Harris said in an announcement about Romney appearing at his fundraiser.

Harris’ fundraising lunch with one of the hottest names in the Republican Party comes as Queen Anne County State’s Attorney Frank Kratovil (D) has been gaining momentum on the fundraising front.

Ever since Maryland’s primary, in which Harris beat incumbent Rep. Wayne Gilchrest (R) in a nasty three-way race, Democratic officials and some former Gilchrest backers have lent strong support to Kratovil’s campaign. Kratovil has positioned himself as the ideological heir of the moderate Congressman and has hired several of Gilchrest’s former staffers to help his campaign. In the meantime, he benefitted greatly from being added to the Democratic Congressional Campaign Committee’s “Red to Blue” fundraising and infrastructure program.

As of the end of June, Kratovil reported $454,000 in cash on hand and $811,000 raised for the cycle (with $376,000 of that money coming in between April and June).

Harris reported $609,000 in cash on hand, a total that includes a $100,000 personal loan that Harris made to his campaign on the last day of the June reporting period.

Harris raised $532,000 during the second quarter and a massive $2.03 million for the cycle. But his high-profile and expensive primary battle in February forced his campaign to essentially start from scratch on the fundraising front.