BLOOMINGTON, Ind. — Outside groups have made almost $3.5 million in independent expenditures so far in the competitive Indiana GOP Senate primary, according to online data from the Federal Election Commission.

The bulk of the spending, about $2.3 million so far, has been by groups supporting state Treasurer Richard Mourdock’s effort to defeat six-term Sen. Dick Lugar. For example, in the past 24 hours, the Club for Growth put down a $421,000 media buy blasting the Senator.

But it’s still not more money than Lugar’s campaign has spent so far. His most recent fundraising report showed his campaign had spent $5.4 million through April 18. Meanwhile, Mourdock’s campaign will report spending just more than $2 million through the same date, according to his spokesman.

Roll Call calculated the breakdown of all the outside spending in the race:

In Lugar’s corner:

• American Action Network spent $645,000, mostly on a television media buy.
• Hoosiers for Economic Growth and Jobs, a super PAC, dropped $215,000 in television media buys.
• Indiana Values Super PAC put $137,000 into the race, also for media and January polling from Public Opinion Strategies.
• YG Network spent $105,000 for mailers on Lugar’s behalf.

In Mourdock’s corner:

• The Club for Growth has spent $1.67 million on his behalf, including its largest ad buy yet in the race placed Wednesday — about $421,000 in television time.
• FreedomWorks spent about $358,00, mostly on travel and campaign gear like signage.
• The National Rifle Association’s political arm spent $323,00 on advertisements, mail and phone banks.

Majority PAC, a Democratic super PAC, spent $17,500 on online advertisements targeting Lugar. Democrats waded into the primary because they see a better chance of picking up the Senate seat if Mourdock is the GOP nominee.