Ted Cruz and Marco Rubio fought to a near-draw in the battle for campaign cash since launching their presidential campaigns this spring, making the summer fundraising months a pivotal period for both candidates.

Cruz, a Texas senator, closed the second quarter with an edge over Rubio, raising roughly $10 million in April, May and June, compared to the Florida senator's $8.9 million. Cruz has raised more money overall since entering the GOP primary, raking in $14.3 million to Rubio's $12.2 million, including more from small donors ($5.8 million versus $2.1 million.) But the Texan also entered the race three weeks before Rubio, giving him an extra 21 days to fundraise.

"It is clear the reports show Cruz is a well-funded conservative that can beat the Establishment candidate. He raised more hard money than any other Republican in the race, including Jeb Bush, and has built a fundraising operation that will sustain the campaign for the long-term," Rick Tyler, the Cruz campaign's national spokesman, told the Washington Examiner. "He can raise all across the country and his relatively low average donation amount means he will have sustainable grassroots support. We will continue to build off of this foundation and look forward to having another healthy quarter."

The Rubio campaign declined to comment for this story.

Rubio's additional haul, beyond the $8.9 million he raised after entering the 2016 contest April 13, two weeks into the second quarter, came from a $3.3 million transfer from his Senate campaign account. But the Rubio essentially converted his Senate donors to presidential donors, and anyone who contributed the maximum of $2,700 to that $3.3 million cannot be solicited again for the primary campaign. Cruz' $14.3 million included a $250,000 transfer from his Senate account.

Cruz finished the second quarter with $8.5 million in the bank; Rubio ended the period with $9.9 million in cash on hand. Figures were confirmed by reviewing Federal Election Commission reports. Those filings were due Wednesday. The candidates are now almost three weeks into the new quarterly fundraising period.

Traditionally, raising political money in July, August and early September is difficult, making the third quarter a tough slog. People vacation with their families in the summer, and even reliable campaign contributors — more interested in politics than average Americans — are focused elsewhere, similar to holiday time in November and December. That could be magnified by the fact that more than 15 Republicans have declared for president, making the fundraising competition super intense.

The first Republican debate, on Aug. 6 in Cleveland, could give them a reason to pay attention and open the spigot during this slow period.

That's important for candidates trying to build a war chest for the fall, when the run for the GOP nomination is likely to accelerate. When it comes to resources, at least, former Florida Gov. Jeb Bush is the candidate all the others are chasing. Bush raised $11.4 million during the last two weeks of June, which were his first two weeks as an official presidential candidate.

"This summer will be different because of the first debate," said a Republican fundraiser who has worked for presidential candidates. "If something happens, and it has to be seen as some sort of game-changer for someone — not just a okay job at the debate — that could increase someone's numbers, or hurt them."

Bush leads all Republican candidates nationally with GOP primary voters, according to the RealClearPolitics average of recent polls, with 15.5 percent. He's followed closely by billionaire businessman/entertainer Donald Trump, who is self-financing his campaign, with 15 percent. Sen. Rand Paul of Kentucky was in fourth with 6.3 percent, followed by Rubio with 6 percent. Cruz was eighth with 5.5 percent and Sen. Lindsey Graham of South Carolina was fifteenth with 0.3 percent.

Among the four senators running for president, Paul and Graham ranked third and fourth, respectively, in the second quarter money chase, making next month's Fox News debate a crucial test — and opportunity — for each of them, although Graham appears unlikely to qualify. The network is only allowing the top ten candidates onto the stage, based on the average of most recent national primary polls as of Aug. 4.

Paul, a libertarian-leaning Republican who has always maintained a healthy grassroots following, raised $5.3 million between April 7, the day he entered the race, and the end of June. Paul transferred $1.6 million from his Senate campaign account to his presidential campaign, giving him a total cash intake of $6.9 million and money available to spend of $4.2 million. Paul raised a robust $3.2 million from small, presumably grassroots donors.

Graham, who declared for president June 1, raised $2.2 million in quarter two, finishing the period with $3.7 million raised after transferring $1.5 million from his Senate account. Graham had $2.6 million in cash on hand.

Disclosure: The author's wife works as an adviser to Scott Walker.