Picture this scenario. The Senate holds a high-profile vote on a proposal focused directly on implementing the Buffett Rule, one that would bring the current tax rate for millionaires paying lower rates on investments up to 30 percent. This, at at exactly the moment when the GOP is picking a nominee who is worth $250 million and is personally benefitting to an enormous degree from the current rate — one that’s lower than many middle class taxpayers pay.

It could happen. I’m told that Senator Sheldon Whitehouse is set to announce a proposal to do just this. The Senate Dem leadership is not commenting on this idea, but Dem leaders are looking for ways to hold votes on the agenda Obama laid out in his State of the Union speech. This would accomplish that perfectly.

Harry Reid has spoken positively about the general idea of a vote on the Buffett Rule, so it seems likely that Whitehouse’s idea will get serious consideration.

Whitehouse’s office shared some details of the proposal — which is called “Paying A Fair Share Act,” and will be introduced by Whiteouse next week.

The bill would ensure that taxpayers who make over $1 million would pay at least a 30 percent tax rate on all their income, Whitehouse aides say. It would do this by requiring millionaires to calculate their overall effective tax rate under the regular system — by taking into account all their sources of income and the various rates they are taxed at.

Those taxpayers whose effective rate is under 30 pecent would be required to pay taxes on all their income at the 30 percent rate. (Charitable contributions that are deductible under the current system would be exempt from income calculations.)

Whitehouse plans to begin building support for the proposal among Democratic colleagues next week. Aides say he’s already reached out to other Senate Dems and gotten positive feedback. Whitehouse has been working on this proposal independently for months.

Senate Democratic leaders have already suggested they are likely to bring Obama’s State of the Union proposals that Obama laid out in his State of the Union to a vote in some form or other, perhaps as part of a package.

Whitehouse is hoping for a vote on his legislation, which would require Republicans to take a Yes or No stand directly on the Buffett Rule itself.

“In these tough economic times, it’s important that millionaires and billionaires are paying their fair share, and that middle class families are getting a straight deal,” one Whitehouse aide said. “This bill would be one step in that direction.”