The Arizona Republic has the story:

The race for Congress in southern Arizona, deemed one of the most important in the nation, has deteriorated into a harsh demonstration of Republican disarray.

With dissension in GOP ranks, Democrats stand a better chance of picking up one of the 15 seats nationwide they would need for a majority in the House. [snip]

Party officials wouldn't discuss why they've bought a reported $122,000 in television ads touting Steve Huffman, who is behind in the polls, but the implication is that the party thinks front-runner Randy Graf can't beat a Democrat.

The TV ads are the national committee's only investment in advertising in a contested primary this year. A state or national party rarely expresses a preference for a primary candidate, much less provides independent advertising.

Democrats have stepped in with ads of their own attacking Huffman's record as a state lawmaker for eight years. It is the only case this year in which the party has targeted a primary opponent, and it, too, signals that Democrats see Graf as easier to beat than Huffman.