Butler County Sheriff Richard K. Jones, who has developed an enthusiastic conservative following for his crusade against local companies hiring illegal immigrants, reportedly is forming an exploratory committee as a first step to running against Boehner of West Chester.

"I can tell you he's serious about it," said Butler County Chief Deputy Anthony Dwyer. "In the not-too-distant future, he'll probably make a decision."

Although Boehner would be a heavy favorite to win a primary, a challenge by Jones would force Boehner to pour money into winning re-election instead of devoting his efforts to helping Republican candidates across the country.

"John will win, but it will be nasty," said Barry Bennett, chief of staff to Rep. Jean Schmidt, R-Loveland. "(Boehner) is incredibly popular. It's a Republican district, and the Republican primary voters don't often toss out incumbents."

The issue of immigration likely would dominate a primary. In 2005, Boehner was one of 17 House Republicans to vote against an immigration bill that called for construction of a fence along the Mexican border.

Jessica Towhey, a Boehner spokeswoman, said Boehner opposed the measure because it included sanctions against employers who hired illegal immigrants. Boehner thought that any employer sanctions needed to be approved by a committee for which he was chairman at the time, the House Education and Workforce Committee.

"The vote was a symbolic gesture of defiance to the leadership at the time," Towhey said.

In 2006, Boehner co-sponsored a bill that called for building a fence along the border. The measure won congressional approval and was signed into law by then-President George W. Bush.

jtorry@dispatch.com