Sarah Palin is back on the campaign trail.

No, she’s not running for president or emerging as a major surrogate for Mitt Romney’s presidential campaign. She’s turned her attention to the battle for the Senate, where she’s lending a hand to her preferred candidates in Republican primaries and playing an increasingly visible role on the stump.

Sarah Palin, former governor of Alaska and 2008 Republican Vice Presidential candidate speaks at a "Patriots in the Park" tea party rally at the Wayne County Fairgrounds July 14, 2012 in Belleville, Mich. (Bill Pugliano/Getty Images)

In some respects, Palin is no help at all. Yet in others, she’s just what the doctor ordered.

Let’s start with where Palin is an asset. Nearly four years after her surprise selection as Arizona Sen. John McCain’s vice presidential running mate, she remains a big draw for conservatives and has a deeply loyal following among many voters who show up to the polls during GOP primaries.

This makes her earned media potential very powerful. When she comes to town, newspapers and television stations cover her events, and readers and viewers pay attention. Even her detractors take notice.

An endorsement from Palin is a rare occurrence for most Republican candidates for Congress. Even less common is a campaign appearance from the former Alaska governor. That’s what made Palin’s trip to Texas to stump for former state solicitor general Ted Cruz’s Senate campaign late last week somewhat surprising.

Cruz’s aides credit her with revving up enthusiasm in the final days before the July 31 runoff, in which the tea party-favorite upset establishment-backed Lieutenant Governor David Dewhurst.

Cruz’s general consultant Jason Johnson explained that the campaign was in the field with polling on the race every night during the stretch run of the race. On the day Palin visited Texas, Johnson explained, among the roughly one-in-five voters surveyed who said they were getting their information about the race from earned media sources, Cruz was leading Dewhurst 58 percent to 33 percent. The next night, Cruz’s lead among that slice of field grew, to a 69 percent to 27 percent margin.

“I’ve certainly never seen an overnight 17-point swing from earned media based on the appearance of a former elected official, a celebrity, or anyone in my experience,” Johnson said.

In Missouri, where Palin is scheduled to stump for former state Treasurer Sarah Steelman Friday and has cut a TV ad for the underdog, the former governor’s strength is her ability to grab viewers’ attention amid the din of nasty ads.

“She cuts through all the noise,” argued Steelman campaign treasurer Jeff Layman. “You have IE X and IE Y, and everybody going at everybody’s throat.”

While Palin’s presence on the trail offers candidates an enticing dose of earned media, she doesn’t help out with her own direct paid media efforts. A review of her political action committee’s financial report though June 30 reveals that she hasn’t made any independent expenditures this cycle.

Other GOP primary power players like the Club For Growth and South Carolina Sen. Jim DeMint’s political committee have devoted a lot of money (in some cases, millions of dollars) to running IE ads on behalf of endorsed candidates. Both the Club and DeMint’s group also excel at bundling candidate donations.

The timing of some of Palin’s endorsements (which have arrived at the last minute, in some cases) is less than ideal for some candidates. And it begs the question of why she doesn’t enter the fray earlier. In Nebraska, for example, Palin backed state Sen. Deb Fischer just a week before her shocking primary win, when Fischer first began gaining traction. If Palin had joined the mix earlier, Fischer might have established some momentum well before the final leg of the race.

But like every politician, Palin must look after her own brand when she considers the candidates with whom she wants to associate herself, because nobody wants to back a loser. A review of the Senate candidates Palin has endorsed this cycle reveals an interesting mix of conservative rebels (Cruz, Steelman and Richard Mourdock in Indiana) and candidates more typically associated with the establishment like Sen. Orrin Hatch (R-Utah) and Rep. Jeff Flake (R-Ariz.).

In other words, pragmatism is not apparently entirely removed from Palin’s calculus.

The decision to play in Senate races could help boost Palin’s brand, so long as she backs winning campaigns. This month, Steelman has a decent shot in a three-way race featuring two men from St. Louis, while Flake appears to have weathered an onslaught of paid media attacks from businessman Wil Cardon. So in the end, the endorsement relationship could prove be something of a symbiotic one for Palin.

This much is for certain: when Palin talks, opponents and advocates alike will listen. As John Coale, a friend of Palin’s put it, “A lot of people follow her lead.”

For Palin, the next month is shaping up as a test of how many voters will take a cue from the former vice presidential nominee. If enough march in lockstep, the candidates she supports won’t be the only ones with something to celebrate.