Thune has been moving full-speed-ahead with his Senate campaign in spite of the lack of an opponent. And unlike governors, who have to rely on meddlesome political action committees to fund their extracurricular activities, everything he’s building for his Senate effort can be put towards a run for president.

There is no word on his first quarter finances, but he had about $6 million in the bank at the end of the year, which was the eight-most of any incumbent senator.

And judging by the campaigns run by recent unopposed senators, he won’t need to spend more than $2-3 million of that – that is, unless he wants to spend it ramping up for 2012.

Put plainly: If he keeps raising big money (in the $1 million-and-higher range) and spends good chunks of it, we’ll have a good idea where his head is at when it comes to 2012.

Of the last seven senators to run unopposed or without major-party opposition, only one spent much more than $3 million. And that candidate – Sen. John KerryJohn Forbes KerryBringing the American election experience to Democratic Republic of the Congo Some Dems sizzle, others see their stock fall on road to 2020 The Hill's 12:30 Report MORE (D-Mass.) – was a candidate for president soon after his easy reelection bid.

Kerry spent more than $9 million on his Senate campaign in 2002 but still had $2.65 million to transfer to his 2004 presidential campaign.

The most recent unopposed senator, Sen. Mark PryorMark PryorMedicaid rollback looms for GOP senators in 2020 Cotton pitches anti-Democrat message to SC delegation Ex-Sen. Kay Hagan joins lobby firm MORE (D-Ark.), spent $2.8 million and had $2.2 million leftover at the end of 2008. Prior to that, Sen. Richard Lugar (R-Ind.) spent $3.1 million in 2006 and Sen. Mike CrapoMichael (Mike) Dean CrapoSenate Banking panel approves Trump's Fed, comptroller nominees Harvey damage adds urgency to flood insurance debate Don't let funding for US Forest Service go up in flames MORE (R-Idaho) spent $1 million in 2004.

In 2002, in addition to the unopposed Kerry, Sens. Pat RobertsCharles (Pat) Patrick RobertsNo. 2 Senate Republican backs McConnell in Trump fight Overnight Healthcare: McConnell warns Senate not to block repeal debate | Insurers knock Cruz proposal | WH tries to discredit CBO | Lawmakers propose .1B NIH funding boost Trump: I’ll be ‘very angry’ if Senate doesn’t pass ObamaCare repeal bill MORE (R-Kan.) and John Warner (R-Va.) spent $1 million and $1.7 million, respectively.

And all of them were running in more expensive media markets than Thune.

Unless Thune goes completely overboard, he’s can walk into the 2012 election cycle with at least $3-5 million in the bank, and possibly more. If he spends any more than that, it should be clear from his expenditures that he’s gearing his efforts toward more than just his home state.

Thune has already made a point to raise money for top GOP Senate candidates this year, and now he can spend even more time helping out others who actually face races this cycle.

Keep a close eye on him over the next seven months.