Monthly fundraising figures have landed at the FEC and the Sunlight Foundation’s Real-Time FEC tracker tool shows national party committees leading the pack, as expected. The fundraising race between the two committees was neck and neck, with each group netting about $9.3 million for the month of April, though the Democratic National Committee carries some $8 million in debt as primary season ramps up.

The political arms of several unions (service employees, teamsters and AFSCME employees) all pulled in more than $1 million through contributions from local chapters. A pair of Tea Party-affiliated committees also were among the top 20 fundraisers, though they spent dearly to raise the cash. The Tea Party Patriots Citizens Fund posted more than $900,000 in receipts for the month of April and spent more than $200,000 on mailers, strategy consultants and donor list rentals. Likewise, the PAC for TeaPartyExpress.org raised just shy of $800,000 and paid a little more than $300,000 to Russo Marsh & Rogers, the Sacramento, Calif., public relations firm that doubles as the committee’s headquarters.

Dark money continues to play a prominent role among outside spending groups. The donors behind some of April’s big political contributions are not known. The Government Integrity Action Fund Network, a super PAC that has spent $1 million on ads for Senate hopeful Tom Cotton, R-Ark., is funded entirely by an associated nonprofit, the Government Integrity Fund. ProPublica reported in April that the fund apparently had violated IRS rules prohibiting so-called social welfare organizations from spending most of their funds on political activity. The group poured most of its money into political ads touting Josh Mandel’s unsuccessful bid to unseat Sen. Sherrod Brown, D-Ohio.

Citizens for a Working America — a super PAC that supported Mitt Romney’s presidential bid — spent $500,000 on TV ads attacking Jack Kingston in Georgia’s crowded Republican primary for Senate. The committee has been fueled by $1.3 million in donations from Jobs and Progress Fund, Inc., a West Chester, Ohio-based corporation that has gone after Illinois Republican Rep. Aaron Schock in the past.

Just one candidate committee cracked the top 20 in terms of total raised. Democrat Valerie Arkoosh, an obstetric anesthesiologist who lost in the primary for Pennsylvania’s 13th District, loaned her campaign $700,000.