Discussions have been preliminary thus far, with sources saying the earliest an actual offer could come would be late this year. Not only because it would take several months to line up financing, but also because private equity firms don’t want the PR hassle associated with bidding for Mitt Romney’s signature business achievement before November 6.

On the surface, Staples makes all sorts of sense as a private equity target. Its valuation has been cut nearly in half over the past two years, and currently is trading at just around 4.45 times EBITDA. The Framingham, Mass.-based company also throws off tons of cash, with nearly $1 billion of net income on more than $25 billion in revenue for the year ending January 27 (although both figures have since declined slightly).

Staples also could benefit in the future from more states beginning to implement sales tax on Internet purchases, a development that some private equity executives believe is inevitable. “Staples not only is the market leader offline, but also has a strong online operation,” says an investor who has looked at the company (note: the investor does not work for Bain). “But that advantage is muted until it gets to compete on an even playing field with Internet-only office supplies companies. I think that day is coming soon and, even though that’s not the primary reason to do this deal, it’s clearly part of the math.”

What really complicates that math, however, is the deal’s size.

Staples currently has market cap of just under $8 billion. Assuming a 20% premium, that would bring the buyout offer to around $9.6 billion (not including assumed debt). The equity check would need to be at least 30% of that, or around $2.9 billion. That likely would require at least three firms to participate, assuming that each one also could get their limited partners to co-invest.

The largest North American buyout funds right now are sized at between $6 billion and $10 billion, so a $1 billion check isn’t as easy to write as it was back in 2006 or 2007. Moreover, some of the interested firms also are circling Best Buy (BBY), and investment committees may get nervous about such a large combined allocation to big-box retailers.

Sources say that leveraged financing would be available for such a deal, although it might require participation by almost all of the largest Wall Street banks.

Spokesmen for both Staples and Bain Capital declined comment.

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