Mr. Obama and the Democratic National Committee spent $70.8 million in June, including about $38 million on television advertising, as the president’s campaign sought to batter Mr. Romney over his ties to Bain Capital, the private equity firm. Mr. Romney and the Republican National Committee spent $38.8 million, including about $11 million on television advertising — more than double what Mr. Romney’s campaign spent in May but far less than Mr. Obama. But because money raised for the election cannot be spent until after the two parties hold their nominating conventions at the end of the summer, Mr. Obama appears to have far more money available to spend in the critical weeks ahead, when each candidate seeks to define the other. Mr. Obama had an estimated $72 million in primary cash available at the end of June, thanks to a vast army of small donors who can give again and again without hitting the $2,500 contribution limit for primary season. Half of Mr. Obama’s money in June came in checks of less than $200. Mr. Romney has an estimated $20 million in primary money. Many of his early donors gave the maximum contribution while he was still spending heavily to fend off his Republican rivals in the first half of the year. But Mr. Romney sharply improved his take from small donors in June, with checks of under $200 accounting for about a third of his fund-raising, suggesting that Mr. Obama’s advantage might not persist. The primary cash for the candidates does not include money not yet transferred to their campaigns from the fund-raising accounts each candidate shares with his party. The deficit in available money leaves Mr. Romney dependent on the Republican-leaning outside groups that have spent heavily in recent months to keep Mr. Obama on the defensive. American Crossroads, the leading Republican “super PAC,” this week announced a new $9 million campaign against Mr. Obama that criticizes the president for what the group says are unfair attacks on Mr. Romney. Restore Our Future, a super PAC backing Mr. Romney, spent about $15 million between April and June, including $7.6 million in June, a month when it raised $20 million. Donations to Restore Our Future included $10 million from the casino billionaire Sheldon Adelson and his wife, $1 million from the real estate developer Harlan Crow, and $2 million from the Texas homebuilder Bob Perry, according to commission reports. Tax-exempt “issue groups” that do not report their donors have spent millions more against Mr. Obama. Mr. Romney has used that breathing room to crisscross the country attending fund-raisers to fill his war chest, exploiting his joint committee with the R.N.C. to bring in checks far in excess of what he could accept for his campaign. The committee, Romney Victory, brought in $140 million in the three months through June. With the primary behind him, Mr. Romney has also begun building out his campaign staff and infrastructure, investments Mr. Obama and the Democrats made months ago. The Romney campaign’s payroll more than doubled between April and June, while his spending on direct mail has more than tripled. He spent close to a half-million dollars on office equipment in May and June. Mr. Romney’s campaign also spent $559,689 in June on “campaign promotional items,” according to election commission reports. Mr. Obama substantially increased his expenditures on polling, spending $2.6 million in June, a fivefold increase over May. He continued to spend heavily on online advertising, with bills of about $4.4 million in June, and data mining, continuing a yearlong effort by Mr. Obama’s campaign to refine its attack on Mr. Romney and reconstitute the vast army of grass-roots supporters that helped power his 2008 victory. Mr. Obama’s spending on events — including stages, sound and lighting — also jumped in June, as he began hitting the campaign trail more intensively. Both candidates are relying heavily on “bundlers,” supporters who gather checks from friends and business associates and help host fund-raisers. A list of bundlers posted by Mr. Obama’s campaign on Friday named individuals and couples. The top rank of bundlers, who have raised at least $500,000 each, included roughly 200 individuals accounting for at least $100 million of Mr. Obama’s haul. Such disclosures are not required, and Mr. Romney has refused to name his fund-raisers. An analysis published this month by USA Today found that Mr. Romney has close to 1,200 bundlers, hundreds of them executives in the financial industry.
