Two hours and two Philadelphia blocks apart, U.S. Sen. Pat Toomey and challenger Joe Sestak traded major policy speeches Friday on Iran, offering the first blow-for-blow exchange of a widely watched Senate election that is still 15 months off.

Toomey (R., Pa.) told an audience at the Jewish Federation of Greater Philadelphia that the Iran nuclear agreement was a threat to national security. He did not mention Sestak. But in a news release earlier in the day, he jabbed at the former Delaware County congressman's support for the deal. That veered from a time-honored tradition of incumbents ignoring their challengers - especially this early in a race.

The first-term Republican called on Congress to pass a resolution disapproving of the agreement, saying, "No deal is better than a bad deal." Sestak, hours earlier, said he "cautiously" supported the deal as a way to make the Middle East "less likely to be engulfed in war."

Talking with reporters after his speech, Toomey brushed off a suggestion that it was unusual for him to single out Sestak - who likely will have to win a contested 2016 Democratic primary before he can take on Toomey.

"I'm going to do everything I can to try to make the case that I believe is the right case, that this is a bad deal," Toomey said. "And if other people are arguing that it's a good deal, I'm going to refute those arguments."

His earlier news release pointed out three of what he called Sestak's "most egregious missteps" on Iran. It said Sestak "has tried to fool Pennsylvanians by misrepresenting the terms of this flawed and dangerous agreement."

The agreement, which would largely limit Iran's nuclear ability for more than a decade in return for the lifting of oil and financial sanctions, has been mostly supported by congressional Democrats and criticized by their Republican counterparts.

Friday's speeches were the latest reminder of the high stakes for both parties in Pennsylvania's 2016 Senate contest. Democrats have labeled Toomey one of the few vulnerable GOP incumbents, and his ouster could help the party's chances of regaining control of the Senate.

But Sestak - who lost narrowly to Toomey in 2010 - is a long way from carrying the Democrats' banner. Katie McGinty, who resigned as Gov. Wolf's chief of staff earlier this month and whom party leaders have encouraged to run, is widely expected to announce a bid soon.

In choosing to engage with Sestak on Iran, Toomey targeted an area that could be considered a strength for Sestak. A former three-star admiral who directed the Navy's antiterrorism unit, Sestak served on the House Armed Services Committee during his time in Congress. Toomey, who serves on the Senate Finance and Banking Committees, has in recent months ramped up his talk on Iran.

Speaking to about 50 people at the Jewish Federation, Toomey said the Iran deal not only undercuts U.S. security, it "seriously jeopardizes Israel's security, which is something I care very deeply about." He criticized the deal for letting Iranian officials force weapons inspectors to wait up to 24 days to inspect a facility.

"Nobody should kid themselves here," said Toomey, whose message was received with nods of agreement and applause. "Like every other radical Islamic terror movement, if Iran is able to inflict harm on Americans, Iran will inflict harm on Americans. And the more harm the better, in the twisted mind-set of this regime."

Sestak, speaking earlier in the day at a Market Street law firm, also brought up Israel - but said the deal benefited that nation's security.

Sestak said he believes the deal sets back the clock for at least a year, if not longer, on Iran's ability to acquire "bomb-grade material for a nuclear weapon."

"Perhaps most significantly, this deal allows the international community to impose meaningful inspections to confirm Iran will not cheat," he said. "What President Ronald Reagan called, 'Trust, but verify.' "

If Toomey has mostly avoided directly engaging Sestak, the same isn't true for the Democrat.

On Friday, for example, Sestak's spokeswoman, Danielle Lynch, said the Market Street venue for his speech was chosen because it was near the site of Toomey's speech at the Jewish Federation's Arch Street headquarters - in hope that reporters "would be able to readily go to both, given the proximity."