Correction: An earlier version of this story said Sen. Thad Cochran appeared at a rally Sunday with Sen. John McCain. That rally was canceled as a result of inclement weather. This version has been corrected.

Sen. Thad Cochran (R-Miss.) speaks to supporters from a pickup truck at a fish fry in Pelahatchie, Miss., on June 17. (Edmund D. Fountain/For The Washington Post)

In this college town’s leafy square on Saturday, Sen. Thad Cochran, fighting for his political life, talked up his hawkish view of foreign policy.

“We need to be sure we’re a force,” he said. “We do have a role to play in protecting our national security interests around the world.”

Outside a hardware store hours later, he discussed his service in the Navy and his four decades procuring federal funds for military projects.

“It’s part of our heritage to defend the country,” he said.

And Monday at a war memorial in Jackson, he will rally with Sen. John McCain (R-Ariz.), one of his party’s most vocal proponents for a muscular foreign policy.

Tea party candidate Chris McDaniel, who is trying to unseat incumbent Sen. Thad Cochran, hugs his two sons, Chamberlain, center, and Cambridge during a campaign rally in Madison, Miss. on June 19. (Jonathan Bachman/Reuters)

In the days before Tuesday’s runoff election to decide Mississippi’s Republican Senate primary, Cochran, lagging behind his tea party challenger, has sharply focused his message on armed-services issues, hoping his years of appropriating millions for the state’s bases and his traditional GOP worldview will give him an eleventh-hour boost.

Cochran’s pitch is a response to the populist fervor that has grown around state Sen. Chris McDaniel, 41, his insurgent opponent who has been endorsed by former Texas congressman Ron Paul, a libertarian Republican and critic of U.S. intervention abroad. It comes amid the unfolding crisis in Iraq, with Cochran arguing that he is a steadier hand.

Cochran, 76, in an interview, described his outlook as that of a “patriotic American,” and he said that he will tout it as he tries to connect with the frustrated conservatives who look unfavorably on his votes to increase federal spending but still support a robust national defense.

Meanwhile, Cochran’s allies will hammer the point even harder, searching for a vulnerability that could damage McDaniel, who in the latest poll by Chism Strategies, a Democratic firm, leads Cochran 52 to 44 percent among those who voted in the primary’s first round this month.

“McDaniel is saddling up with Ron Paul and peaceniks,” said Henry Barbour, a Republican consultant who directs a pro-Cochran political action committee. “Senator Cochran is the only veteran in this race, the only one who deeply understands veterans, our state’s facilities and the importance of promoting freedom.”

Cochran’s move against McDaniel on this front is part of a larger internal debate in the GOP on foreign policy, with older and more middle-of-the-road Republicans who supported the wars in Iraq and Afghanistan clashing with younger tea party conservatives who opposed aspects of those conflicts and have more isolationist leanings.

But Cochran’s emphasis on military affairs, woven throughout softly delivered weekend remarks to small crowds, may not be enough to stall the ascendancy of McDaniel’s grass-roots bid, which has become a cause for national conservative groups and figures, such as Paul and former Alaska governor Sarah Palin.

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About 100 people, toting lawn chairs and bright-red McDaniel signs, showed up Saturday night at a parking lot in Pearl, Miss., for an event hosted by the Tea Party Express. McDaniel did not appear, because of travel issues, but attendees danced as a pop duo sang conservative tunes and listened to a speech by Billy Jack McDaniel, the candidate’s first cousin. On Sunday afternoon, a larger crowd greeted Chris McDaniel at a Hobby Lobby parking lot in Biloxi, roaring approval when a McDaniel surrogate said President Obama should be impeached and booing mentions of Cochran.

McDaniel, who finished slightly ahead of Cochran in the June 3 vote that spurred the runoff, has worked to shake off Cochran’s attempts to tie him to Paul, reassuring recent Republican audiences that in spite of his aversion to most congressional “pork,” he would be a supporter of the state’s sprawling military community.

Stumping in Biloxi, wearing jeans and an untucked shirt, McDaniel recalled that his family has experience in shipbuilding and promised to be a champion for the industry and for the military.

He called military spending “a legitimate function of government,” drawing applause from those in the crowd, many from the nearby Naval Construction Battalion Center in Gulfport.

In most other respects, however, McDaniel has avoided talking much about foreign policy, instead choosing to run on fiscal discipline and the need for more combative conservatives on Capitol Hill, where he says Cochran avoids antagonizing Obama and largely shuns the national spotlight.

McDaniel’s endorsement from Paul has not been a centerpiece of his campaign. He accepted it and is reaching out to Paul’s network of supporters, but he has not embraced Paul’s noninterventionist stance. Noel Fritsch, McDaniel’s spokesman, said McDaniel opposed U.S. action in Syria, the Obama administration’s decision to swap five prisoners for Sgt. Bowe Bergdahl and the nomination of Chuck Hagel as defense secretary, and said those positions gave an indication of his views.

Still, Cochran’s campaign believes that voters in Mississippi, which is dotted with military installations — including Camp McCain, named for the uncle of Sen. McCain’s grandfather — could grow wary of McDaniel if he is seen as a less-than-reliable hawk instead of a fiery hard-liner in the mold of Sen. Ted Cruz (R-Tex.).

Last week, Mississippi Gov. Phil Bryant (R), a top Cochran backer, appeared in an ad, called “Veteran,” that underscored the strategy. “In Mississippi, we support our military,” Bryant says, noting that Cochran is one of the few remaining veterans in a chamber once dominated by them.

McCain’s appearance Monday with Cochran comes after an airport rally near the coast at which they were to appear together Sunday was canceled because of inclement weather. Such appearances with politicians from outside Mississippi have been rare this year for Cochran, who has been intent on casting McDaniel as the creation of Beltway groups.

Cochran, seeking a seventh term, is recruiting Democrats and independents for his coalition as he tries to defy the odds in a runoff election, where turnout typically is lower than the initial vote. Since Mississippi does not register by party, anyone other than those who participated in the June 3 Democratic primary is eligible to vote.

At the Oxford courthouse Saturday, Cochran winked when he handed in his absentee ballot, telling the clerk, “Vote early and vote often.”

He then drove to a tire shop to make direct appeals to black voters. “We don’t want to miss anybody,” he said as he spoke in Batesville, where a line of black mechanics approached him to shake hands. Several of them told Cochran that he could count on their support.

“I’m a Democrat and very concerned about the tea party,” said Lee Roy Sanford, 54, an employee at the shop. “Since Senator Cochran is here, talking about the right things, new jobs and a strong military, I’m making an exception.”

The upside of Cochran’s approach is that thousands of new voters could help him eke out a victory. The risk is that he alienates conservatives even more, including those conservatives who are sympathetic to his position on military spending and foreign policy and nervous about McDaniel’s general-election viability.

At the Tea Party Express rally Saturday, many attendees spoke disparagingly about Cochran’s outreach to Democrats. Some pulled out their phones, reading aloud Facebook posts about pro-Cochran pamphlets being spotted in low-income neighborhoods.

“Cochran made the calculated decision that he had to grow the electorate to win,” said Brad Chism, a Democratic pollster who has been closely tracking the race. “So he had to risk a backlash with conservative rank-and-file Republicans who might be turned off.”

Dan Balz in Washington contributed to this report.