New Hampshire Republican Senate candidate Scott Brown is getting help from Sens. Rand PaulRandal (Rand) Howard PaulRon Paul hospitalized in Texas The Hill's Morning Report - Sponsored by Facebook - Trump previews SCOTUS nominee as 'totally brilliant' Rand Paul says he can't judge 'guilt or innocence' in Breonna Taylor case MORE (R-Ky.) and Marco RubioMarco Antonio RubioGOP lawmakers distance themselves from Trump comments on transfer of power McConnell pushes back on Trump: 'There will be an orderly transition' Graham vows GOP will accept election results after Trump comments MORE (R-Fla.) in the final week of his challenge to Sen. Jeanne ShaheenCynthia (Jeanne) Jeanne ShaheenSenate Democrats introduce bill to sanction Russians over Taliban bounties Trump-backed candidate wins NH GOP Senate primary to take on Shaheen Democratic senator urges Trump to respond to Russian aggression MORE (D-N.H.).

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Paul cut a 15-second ad for the Chamber of Commerce touting Brown, while Rubio penned an editorial for the Union Leader praising the candidate as a "friend" and "simply a better choice" than Shaheen.

Both Paul and Rubio are contemplating presidential runs, and their engagement in the New Hampshire Senate race could have implications not just for Brown's success, but for their own political futures.

In the ad, Paul makes an appeal to New Hampshire's independent-minded electorate, saying "if you're a freedom-loving, liberty-loving, leave-me-the-hell-alone voter," go vote for Brown on Election Day.

Rubio, meanwhile, calls Shaheen a "decent person with whom I’ve had a cordial relationship and worked on some issues," but notes she's voted for President Obama's agenda 99 percent of the time — "an agenda that has saddled us with more debt, more uncertainty about the future at home and abroad, but not enough jobs."

In contrast, Rubio emphasizes Brown's independence and his military experience.

"Scott’s three decades of National Guard service give him a unique perspective to national security debates at a time when the world seems as unstable as ever, and Americans face terror threats that are both foreign and homegrown," he says.

Recent polling has shown Brown closing the gap with Shaheen, with multiple surveys out over the past week showing it within the margin of error. Brown has gained support, New Hampshire political observers say, in part due to an aggressive focus on national security, which appears to be benefitting him as the nation deals with Ebola and the threat of the Islamic State in Iraq and Syria (ISIS).

Shaheen has accused Brown of fear mongering, but he's defended his focus on national security and did so again during a Wednesday morning appearance on "Fox and Friends."

"People in New Hampshire have a rational fear, not only about the border and the border crisis that we have, they have a rational fear about Ebola, obviously about what's happening with ISIS. Absolutely, they're deeply concerned about the direction of our country," he said, blaming the situation on Obama's "half-steps and hesitation," which he said has been "endorsed" by Shaheen 99 percent of the time.