If you re-run the results of the 2010 presidential election without Crimea and Sevastopol, you reduce the margin of the winning candidate, Viktor Yanukovych, against his opponent, Yulia Tymoshenko (pictured above with Yanukovych), by about half.

The final result of the runoff election?

Yanukovych: 48.95%
Tymoshenko: 45.47%
Against all: 4.36%

Now look what happens when you simply remove the votes from Crimea and Sevastopol, where Yanukovych racked up some of his largest margins against Tymoshenko:

Yanukovych: 47.03%
Tymoshenko: 45.11%
Against all / Crimea / Sevastopol: 7.86%

It doesn’t mean that, without his support in Crimea and Sevastopol, Yanukovych would have lost the 2010 presidential race, which everyone at the time considered a relatively free and fair vote.  But it would have made a clear win much messier, perhaps giving Tymoshenko a case to rally against potential election fraud.

That’s something to keep in mind for the future of Ukrainian politics if, as expected, Crimeans vote on March 16 in favor of annexation by Russia (in what will almost certainly not be a free and fair vote).

It probably will have little effect on the scheduled May 25 presidential election, which will almost certainly be won by either Petro Poroshenko, a businessman who supported the anti-Yanukovych protests, or by Vitaliy Klychko, the heavyweight boxing champion and opposition political leader.  But as the old east-west tensions that have become the hallmark of Ukrainian politics reemerge (as they invariably will) for, say, the 2019 presidential election, it will be that much more difficult in a Crimea-less Ukraine for an eastern leader, sympathetic to Russia, to win the Ukrainian presidency in the future.

It’s also worth noting that in the 2012 parliamentary elections, Yanukovych’s eastern, pro-Russian Party of Regions (Партія регіонів) won 11 of 12 single-member districts within Crimea and Sevastopol. (The 12th went to Union, a local pro-Russian party).  In the 2012 elections, Yanukovych changed electoral law to provide that 225 of the 450 seats in Ukraine’s parliament, the Verkhovna Rada, would be determined on a first-past-the-post basis in single-member districts — the idea being that the Party of Regions would win more seats by splitting the opposition, a strategy that largely succeeded for Yanukovych in 2012.  Under the previous 2004 constitution, which has now been reinstated by Ukraine’s parliament in the wake of Yanukovych’s ouster, all 450 seats are determined on the basis of proportional representation through national party vote.