Campaign watchers on both sides of the aisle have a pretty good sense of which U.S. Senate races are likely to be competitive in the fall, with control of the chamber on the line. And in general, Indiana was not at the top of anyone’s list – though some recent developments have made this contest surprisingly interesting.

The way it was supposed to work was pretty simple. Sen. Dan Coats (R) is retiring, and the party establishment quickly rallied behind Rep. Todd Young (R). Given Indiana’s status as the Republicans’ strongest Midwestern state, Young seemed like a safe bet for a promotion.

But the first sign of trouble came last week, with this Politico report

GOP Rep. Todd Young may not have submitted enough valid petition signatures to qualify for Indiana’s Republican Senate primary, putting his rising political career in jeopardy and changing the outlook for an open Senate seat that Republicans expected to hold easily. To win spots on the primary ballot in Indiana, Senate candidates must get at least 500 registered voters in each congressional district to sign nominating petitions. But multiple hand counts of Young’s petitions conducted by the Indiana Democratic Party found just 498 valid signatures from Indiana’s 1st District, and the party now plans to challenge Young’s eligibility for the ballot.

In this case, “close enough” doesn’t really count as a proper legal standard. Young needed to submit 500 signatures in each congressional district, and according to Democratic hard counts, in Indiana’s 1st district, he submitted 498.

When the Indiana Democratic Party moved forward with a challenge to Young’s eligibility, the National Republican Senatorial Committee accused Dems of “trying to deprive the voters of Indiana of legitimate choice.” Republicans did not comment, however, on the Young campaign’s apparent difficulty in meeting the minimum legal requirement.

Making matters just a little more interesting, the Indianapolis Star reported over the weekend that Young’s candidacy is facing another challenge, this time from a Republican rival.

Republican Todd Young is facing a second challenge to his right to be on the ballot for Indiana’s Senate race – this time from fellow GOP Senate candidate Marlin Stutzman. A Stutzman campaign aide Friday filed a challenge similar to the Democratic Party’s contention that Young did not collect enough signatures from registered voters…. By filing a separate challenge, the Stutzman campaign can make its own arguments to the board for why Young, the only other Republican in the race, should not be on the ballot.

Making this just a little more interesting still, the Indianapolis Star did its own hand count of the petition signatures in Indiana’s 1st district, and the newspaper counted 497 – a tally that’s one signature lower than the Democratic count, but consistent with the number the Stutzman campaign came up with.