The difference between "likely voters" and "registered voters" may make the difference for the campaigns of Democratic Sen. Jeanne Shaheen and her Republican opponent Scott Brown.

In a CNN and ORC International poll, a majority of 1,039 New Hampshire residents have their "mind made up" in the race between the incumbent Shaheen or former Massachusetts senator Brown. Among the 735 likely voters, Brown and Shaheen are tied at 48 percent. But registered voters favored Shaheen with 51 percent while Brown garnered 44 percent. While more registered voters favored Shaheen, 21 percent of the same group said they "might change their mind."

Brown might need to further his likeability efforts. The Republican challenger holds a 46 percent favorable rating from likely voters and 44 percent from registered voters. The unfavorable rating among likely voter for Brown is 48 percent, while registered voters responded with 47 percent.

Gender also made a difference for the Senate candidates as 54 percent of women favored Shaheen, and the same percentage of men preferred Brown.

Despite a Latino population of 3.2 percent, the CNN and ORC International poll did not breakdown how Latinos respondents voted.

While the Senate candidates make their efforts to satisfy New Hampshire voters, Brown and Shaheen have introduced foreign affairs into their debate. With the potential threat of the Islamic State, also known as ISIL (Islamic State of Iraq and the Levant), Shaheen commented on Obama's decision to launch aerial attacks against the militant group.

"While I recognize that the President has some existing authorities to target ISIL, I strongly believe he should come to Congress to get the authorization and bipartisan political support that will be required for the long-term fight to destroy these terrorists," said Shaheen, a member of the Foreign Relations Committee.

Shaheen added that she supports having the committee draft a "tailored Authorization for the Use of Military Force." She said it's important to debate such an authorization issue with Congress.

Utilizing the fact Shaheen is still a congresswoman, Brown's campaign office announced the former Massachusetts senator sent a letter to the incumbent to ensure Congress debates two issues: U.S. border security and the Islamic State.

"I continue to be concerned that Americans will not be safe and we will not have a sound national security policy so long as our borders are continually trespassed by people entering the country illegally. By failing to secure the borders and willfully refusing to enforce the laws that Congress passed and past presidents signed into law, the White House continues to put our neighbors here in New Hampshire and around the country at risk," Brown wrote, noting he supports Obama's decision to attack the Islamic militant group.

According to Brown, the situation at the border could allow anyone, including members of the Islamic State, to enter the U.S. "at any time." While Brown admitted that he doesn't know where ISIL and its supporters are plotting a potential attack, he said the Obama administration has done little to protect Americans from the militant group's "very real threats."

"We need to secure our borders as the first step in any immigration reform, but now it has become a national security imperative. ... There is no defensible excuse for the President and Congress to shirk their duty to enforce our immigration laws, a failure which undermines the will of the people and now puts them at risk," Brown said.