Ruth Meier, from Silver Lake, Kan, votes at the Prairie Home Cemetery building, Tuesday, Nov. 4, 2014, in Topeka, Kan. (AP Photo/Charlie Riedel)

Topeka ? Before Gov. Sam Brownback called last week for a special session to deal with school finance issues, most Kansas legislators, as well as candidates hoping to become legislators, had already shifted into full campaign mode.

And with a large number of incumbent lawmakers facing primary challenges, the ad wars have already begun.

“Standing up to a sitting governor to defend the defenseless. That’s exactly the kind of common sense and courage we need in office,” says one political ad already running on many Topeka-area radio stations.

The ad is from Republican Joe Patton, a former Kansas House member — and viewed by many as a conservative ally of Brownback’s — who is now trying, for his second time, to unseat incumbent Republican Sen. Vicki Schmidt.

In many ways, it shows not only what the major theme of this year’s campaign will be, but also how campaign strategies are changing in the face of new trends, including the growing use of advance voting.

Patton recently spent just more than $16,000 buying airtime on two radio groups in the Topeka area: Alpha Media, which owns three stations in the market plus the Kansas Ag Network, and Cumulus Broadcasting, which owns six more stations.

Alpha Media advertising director Dan Lindquist said it’s unusual to see candidates go on air with advertising this early in the season because the so-called “political window” set by the Federal Communications Commission hasn’t yet started.

That’s the period that generally runs 45 days before a primary election, and 60 days before a general election, when broadcasters have to offer candidates the lowest rates that they charge other advertising clients during the same time slot.

“We actually charged him the full rate,” Lindquist said of the Patton ads.

But Senate Democratic Leader Anthony Hensley of Topeka, who works with Democratic candidates and monitors election trends, said that regardless of FCC rules, candidates are increasingly being forced to start advertising earlier because growth in advance voting has effectively shortened the election season.

“The primary is two months away, and with the advance voting starting early in July, I’d say you want to get out sooner than usual,” he said. “A lot of people take advantage of advance voting.”

According to the Kansas Secretary of State’s office, 19 percent to 20 percent of all ballots cast in the last four election cycles have been cast in advance, either by people mailing them in or voting in person at a county election office.

The Schmidt-Patton rematch is expected to be a hotly contested race. Four years ago, Schmidt spent just more than $200,000 defending herself in the primary, compared with Patton’s $49,000, and won the race by a mere 160 votes, or 1.5 percent.

At that time, Patton was among several conservatives who were working to oust moderates from control of the Senate, although he was not part of the group that Brownback and several outside groups recruited and endorsed.

“I do not support these policies from this Governor and this legislature. It’s a mess,” Patton said in an email. “The budget is a disaster, and it is threatening education.”

According to legislative records, though, Patton was among the 64 House members in 2012 who voted in favor of the sweeping income tax cuts that many argue are the reason for the state’s recent budget woes.

Schmidt, who was in the Senate that year, also voted in favor of the tax cuts.

Schmidt was among the very few relative moderates who survived those primaries, but Patton’s latest ad seems to illustrate how even conservative candidates this year are trying to put distance between themselves and Brownback, whose approval ratings have fallen into the 20-percent range.

Elsewhere in Kansas, First District Congressman Tim Huelskamp, R-Fowler, has already spent more than $1,600 buying TV time through the Cox Communications cable system. His ads are scheduled to run through June 19, just when the lower-cost political window opens.

Huelskamp, who had an unexpectedly tough primary challenge in 2014, faces another primary challenge this year: Roger Marshall, a Great Bend physician who reported in March that he had already raised more than $700,000 since launching his campaign last year, outpacing Huelskamp’s own fundraising.

So far, at least, the rush to get on the air early hasn’t taken hold in the Kansas City market, where advertising time tends to be significantly more expensive.

Dan Larson, an account manager with the seven-station Cumulus group in that area, said he doesn’t expect to see Kansas legislative candidates go on air, at least until after the FCC’s political window opens next weekend, June 18.

A search last week of public files at two of the major radio groups in the Kansas City market, Cumulus and Entercom Kansas City, which owns eight radio stations in the market, showed no Kansas candidates had yet bought time on those stations.

But those stations are awash with ads from the Missouri side of the market, where there is an open governor’s race and independent groups are advertising heavily both for and against enacting legislation to limit the power of labor unions.

Larson said he does expect to see some ads on the Kansas side, from candidates and independent groups. But he said the candidate ads will come mainly from congressional and state Senate candidates because Kansas House districts are too small to justify the cost of radio time.

There will be a primary in the Third Congressional District where Republican incumbent Kevin Yoder, of Overland Park, faces Greg Goode, of Louisburg.

Goode just launched his campaign in May and hasn’t yet filed his first campaign finance statement, while Yoder reported having $2.3 million in his war chest in March.

But there are two Republican primaries in the Johnson County area in Kansas Senate races that are expected to be highly competitive and could draw significant advertising dollars.

They include the 11th Senate District, where incumbent Jeff Melcher, of Leawood, faces John Skubal, of Overland Park; and the 21st District where incumbent Greg Smith, of Overland Park, is being challenged by Dinah Sykes, of Lenexa.