Story highlights Ebola, ISIS and immigration were all features of a debate that turned on fear

Jeanne Shaheen said Scott Brown was "fear-mongering"

Brown called his fears rational

Democratic Sen. Jeanne Shaheen repeatedly accused Republican challenger Scott Brown of "fear-mongering" -- on Ebola, ISIS and more -- in the second debate of a New Hampshire race that's key to determining which party will control the Senate.

But Brown shot back that his are "rational fears" shared by a majority of Americans.

The race a dead heat. A CNN/ORC International poll released Thursday found Shaheen with 49 percent support to Brown's 47 percent -- well inside its margin of error of plus or minus four percentage points.

It could turn on whether Shaheen is able to keep on her side voters who have turned on Obama. His approval rating dropped to 39 percent in New Hampshire -- which has driven Brown's efforts to connect Shaheen with the president.

And that's what Brown tried to do, using every issue possible -- illegal immigration, Ebola, ISIS and Obamacare among them -- to try to nationalize the debate.

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Shaheen, meanwhile, cast Brown as a political opportunist and turned to Democrats' bread-and-butter economic topics like equal pay and raising the minimum wage.

Here are six lines that showcased the debate's top issues:

Scott Brown: "She calls it fear-mongering; I call it rational fear."

The day another potential Ebola case was reported -- this time, a doctor in New York -- the two sparred over the Obama administration's handling of the threat.

Brown called for a ban on travel from the West African epicenter of the outbreak. He blasted Obama's appointment of Ron Klain as the nation's Ebola response coordinator as someone "with no experience in his field." He criticized Shaheen for not voting to close the U.S. border with Mexico. And he complained that the New York doctor should have been quarantined when he returned to the United States.

Brown even said the Ebola threat would be minimized if Republican Mitt Romney had been elected president.

"Had he been president, I feel he would have had a clear and concise plan. He would have reassured the American people," Brown said.

Shaheen, meanwhile, criticized Brown for "fear-mongering about this issue," and said neither she nor Brown have medical expertise on the issue.

But Brown shot back that "she calls it fear-mongering; I call it rational fear."

Jeanne Shaheen: "I don't think it makes sense for the president to come to New Hampshire right now."

Just like he has through the entire race, Brown repeatedly tied Shaheen to Obama -- whose approval rating, a CNN/ORC International poll released Thursday found, is 39 percent in New Hampshire.

The political damage that association can cause Shaheen was most clear when she said she didn't want Obama to campaign for her.

"The fact is, that there are big differences in this race between my opponent and me, and it's not just about the president," Shaheen said, repeatedly turning to issues like increasing the minimum wage and mandating equal pay.

Brown said on a number of issues, Shaheen and Obama might as well be the same person.

He said she's already supported the president's agenda for six years, and said she cast the deciding vote to approve Obama's signature health care law.

"There were 60 of us," Shaheen said, referring to the Senate's 60 Democrats at the time, all of whom supported Obamacare. "Every one of us was a deciding vote."

Brown: "There is a rational fear ... [of] criminal elements, terrorists, people with diseases coming through our border."

Illegal immigration appeared to be Brown's comfort zone. He repeatedly returned to the issue, asserting that weak border security could open the United States up to an influx of ISIS fighters, victims of the Ebola virus and more.

He criticized Shaheen's support for the DREAM Act, for failing to crack down on undocumented immigrants who receive government benefits and for standing by as Obama moves toward executive action on immigration after the Nov. 4 election.

He said he'd never support any bills that would "actually legalize people that are here illegally, who are not entitled to the protections and/or the rights and privileges that have been earned by our citizens."

Shaheen, meanwhile, cast Brown's position as unworkable. "The fact is," she said, "if you want border security, then you should support comprehensive immigration reform."

She criticized Brown for voting in favor of a GOP budget that would have slashed homeland security spending, and for missing committee hearings on border security.

Shaheen: "We don't need to import a candidate who's going to outsource our jobs."

The Democrat landed two punches in one line -- hitting Brown, the former Massachusetts senator, for moving into his native state to mount another Senate campaign and then pivoting to economic issues.

She pointed repeatedly to Brown's support for oil industry subsidies, accused him of doing the bidding of large corporate interests and even tried to latch Brown to the Koch brothers, the conservative political funding giants who she said have pumped $2.6 million into New Hampshire's race.

The two debated Shaheen's zero rating with the National Federation of Independent Businesses -- with Brown repeatedly citing that figure and Shaheen dismissing it, arguing that the organization is funded by the Koch brothers.

Moderator Wolf Blitzer pointed out that using Congressional Quarterly's scoring, Brown, while representing Massachusetts, voted with Obama 78 percent of the time.

"Well when the president does something right, I'll support him," he said. "As an independent senator, I can do that."

Brown: "We've taken the greatest fighting force off the table."

Brown accused Obama -- and, by extension, Shaheen -- of blowing the United States' chances of defeating ISIS in Iraq and Syria by insisting that ground forces won't be part of an effort that so far has included air strikes.

"What if air strikes don't work? Then what?" Brown said. He pointed to a new book by former Defense Secretary Leon Panetta accusing Obama of "half-steps and missteps, and as a result our allies don't trust us, our foes don't fear and respect us, it's been an incoherent policy."

Shaheen responded that the United States is "building an international coalition" that includes 60 partners, including some Arab countries. She looked for wiggle room, saying she would take sending ground troops to the region off the table "right now."

"I don't think we should be putting tens of thousands of American troops back in as an occupying force, and we should also not be talking about ISIS in a way that spreads fear and panic among our population," she said. "That's just grandstanding."

Shaheen: "We should make sure that people can make a living."

She tried to back Brown into a corner on whether he supports raising the minimum wage.

Shaheen said women -- who support her over Brown -- would make up two-thirds of the beneficiaries of an increase in the minimum wage. National Democrats have called for a new figure of $10.10 per hour.

"This is one of the issues that distinguishes me from my opponent, because I have been supporting middle class families here," she said. "I think it's now clear that he doesn't support that."

Brown said his mother worked minimum wage jobs, and that he did, as well, earning his first paychecks at a Dunkin' Donuts. He said he's supported increases in the past. But he didn't say whether he supports an increase now, instead accusing Obama and Shaheen of trying to "dictate" to businesses already burdened by overregulation.

"What's happening right now is another effort by the Obama administration, as supported by Sen. Shaheen, to just dictate to businesses what they're going to pay," he said.