WATERTOWN — $857,120.64 can buy a lot of things.

It could buy you a waterfront home in the Adirondacks or on the St. Lawrence River, close the gap in the Edwards-Knox Central School District budget, land you some coveted Beatles memorabilia or get you a small yacht.

It could even, if spent in the right places, buy you a congressional district.

American Crossroads, a GOP super PAC co-founded by Karl Rove, and New York 2014, a super PAC headed by 2006 gubernatorial candidate John J. Faso, have spent $857,120.64 on television ads and postage, printing and production of fliers supporting Republican Elise M. Stefanik and opposing Republican Matthew A. Doheny in the race for New York’s 21st Congressional District.

The two candidates will face each other in a June 24 primary election.

It’s a lot of money. But in a district accustomed to large quantities of outside spending in recent years, the bigger question is, “Why this race?”

“The GOP establishment is running for its life,” said John Zogby, founder of the Zogby poll. “This is good establishment territory; it’s more conservative than San Francisco and New York City but it has a moderate, independent streak.”

According to Mr. Zogby, Karl Rove — “Mr. Establishment” — may be looking for a candidate who has “intersected with the establishment and who will be around for a while.”

They may have found that candidate in Ms. Stefanik, a 29-year-old Harvard graduate who spent her early professional years working in the George W. Bush White House, overlapping with Mr. Rove’s tenure there.

“Looking at this one, we have a unique case here,” said Richard Benedetto, adjunct professor of journalism at the School of Public Affairs at American University. “Why would they pick that race? She worked in the White House. Karl Rove worked in the White House. He’s a friend. He’s helping her out.”

The two experts view the involvement of Mr. Rove’s super PAC in different terms.

For Mr. Benedetto, it comes down to a personal connection. For Mr. Zogby, it’s part of an effort by the Republican establishment to prove its viability to the intransigent tea party movement.

Depending on which one is correct, the two diagnoses could have very different consequences.

American Crossroads’ two large media buys in the district, one for $228,366 on May 30 and one for $228,671.50 on June 6, signal the super PAC’s first involvement in a House primary between two fairly moderate candidates. In both of their televised debates, Mr. Doheny and Ms. Stefanik agreed on a majority of issues.

But in a year of several challenges from tea party conservatives and in the wake of a stunning primary loss by House Majority Leader Eric Cantor, R-Va., the Republican Party establishment may be working out a strategy to prove that it can win not only primary but general elections, according to Mr. Zogby.

“It’s a valid observation,” Mr. Benedetto said. “The narrative of the Republican Party this year is the establishment fending off tea party challengers.”

But Mr. Benedetto sees the involvement of American Crossroads in the race between Mr. Doheny and Ms. Stefanik as a singular event and not part of a larger strategy.

“There’s not a big contrast between the two; it’s the connection more than the ideology,” he said.

Whatever the thinking behind the group’s tactics, it seems to be working, according to Mr. Zogby.

“They wouldn’t be spending if they didn’t think they had a chance,” he said. “And they wouldn’t be doing a second buy if it wasn’t having some kind of effect. It must be working.”