The financial tide has turned against Republican presidential candidate Mitt Romney and his key allies, who spent more than they brought in and were outraised by President Obama during the month of August, according to disclosures filed Thursday.

Romney’s presidential campaign committee raised nearly $67 million last month — a strong figure — but spent about the same amount building its campaign organization and responding to a barrage of attack ads from Obama and his allies. Even so, the campaign spent just $13.7 million on ads, which was less than the $15 million it spent in July.

Romney was also forced to take out a $20 million loan because the campaign had run out of money raised during the primary season. The campaign also fell behind in its attempts to reach grass-roots donors despite the addition of tea party favorite Paul Ryan to the ticket, records show.

The spending left the campaign with about $50 million cash on hand at the start of September, not including the remaining debt, according to the disclosures.

Obama’s campaign account, by contrast, had nearly $90 million on hand going into September, even after spending $83 million in August. Officials said Obama had 1.19 million donors last month — more than a third of its total for the 2012 cycle.

The main super PAC supporting Romney, called Restore Our Future, spent nearly three times as much as it raised in August, devoting more than $20 million to broadcast ads, filings show. The group reported having $6 million left on Aug. 31.

On Aug. 31, Romney handed out more than $200,000 in bonuses to top employees, including $37,500 to national political director Richard Beeson and $25,000 each to a half dozen others, the records show.

Priorities USA Action, a super PAC devoted to helping Obama that has lagged far behind its conservative rivals, posted its strongest month in August by raising $10.1 million, including $2 million from hedge-fund manager Jim Simons. The group spent $9.5 million and had $4.8 million in cash.

The numbers signal a financial shift away from the Republicans after a summer of Democratic hand-wringing over fundraising. The Obama campaign argues it is likely to be outmatched by conservative super PACs and nonprofit groups, which can raise unlimited funds from wealthy individuals and corporations and are working to build a ground game to match them.

The Romney campaign and the Republican National Committee had outraised Obama and the Democratic National Committee for three months starting in May. But the Obama team edged out Romney and the GOP last month by $114 million to $112 million, according to general numbers announced earlier this month.

In addition to his cash-flow problems, Romney had more trouble raising money from grass-roots donors in August, with just 14 percent of his total coming from contributions of $200 or less — a significant drop from the month before. Obama collected about 30 percent of his August haul from donors giving $200 or less.

Romney, however, continued to do well among the wealthiest donors who are able to legally give more than $70,000 to the Romney campaign, the RNC and associated committees. Romney and the RNC say they had a total of $170 million in cash on hand at the end of August.

Most of that money, however, went to allied committees and remains outside Romney’s direct control, which could have serious ramifications for ad purchases and other strategy in the last six weeks of the campaign. Party committees and outside groups do not qualify for the lowest ad rates, meaning their money does not go as far in media spending.