Paul Kane has a good update today on the battle for the Senate, which now appears to be just about dead even, at least as far as anyone can tell from this far out. The basic story has been that the playing field this cycle favored Republicans because far more Democratic seats were up six years after the 2006 Democratic landslide, and then initially retirements and recruiting appeared to solidify Republican gains, especially the retirements in Nebraska and North Dakota. However, the tide turned back the other way recently: The Democrats had a run of good recruiting (in Massachusetts and, I suppose, Nebraska); Olympia Snowe’s retirement was a big Republican setback; Republicans failed to find strong candidates in a few states; and in others, including North Dakota, early polling has found more Democratic strength than expected.

Add it all up, and there’s considerable uncertainty about what the 113th Senate will look like. Doug Mataconis goes deep into the details and says the best-case outcomes for the Republicans is getting up to as many as 54 Senators, while a best-case scenario for the Democrats has them picking up three seats to reach 56. That looks right to me, although I’d add a non-zero chance for an additional Democratic gain in Arizona and a non-zero chance for additional Republican gains in any of several Democratic seats that currently look relatively safe, including Michigan and Ohio.

What interests me about this is that it’s the perfect condition for centrist Senate reform: control of both the Senate and the White House (and, to a lesser extent, the House) are completely up in the air at this point. Ezra Klein has advocated a version of this, with reform phased in over time so neither party would know who would benefit – but if they passed something now to take effect in January, that would basically have the same effect.

My sense has always been, however, that we’re far more likely to get partisan Senate reform, most likely the next time there are at least two consecutive Congresses of unified government. As Senate dysfunction grows, however, I now think it might happen even sooner, in the first couple of years of unified government without a supermajority in the Senate. My guess? A Democratic landslide this year (unified control, 53-56 Senators) probably means reform is likely sometime in 2013; a GOP landslide (unified control, 52-68 Senators) probably sets the close to 2014 or 2015. Only a mixed result – Romney wins but Democrats hang on to the Senate, Obama wins but Republicans hold the House – delays reform further.

Either way, my plea to reform advocates, especially those who don’t want the Senate to wind up looking the way the House does now, is simple: get ready now. Have your proposals ready to go, because sooner or later – and perhaps sooner than anyone expects – reform of some kind is coming to the Senate.