Deputies from the Ukrainian Democratic Alliance for Reforms (Udar), led by heavyweight boxing champion Vitali Klitschko, and the Batkivshchyna (Fatherland) party -- who are allied under the Ukrainian Democratic Alliance for Opposition banner -- began their protest on February 5.
The aim is to put a halt to what's become known in Ukraine and Russia as "piano voting," in which deputies present in the chamber press the electronic voting buttons for absentee colleagues.
They are asking for a fingerprint-recognition system to be implemented so that a deputy would have to be present in order to vote.
It's a problem that's frequently solved in the West through what's known as "pairing," whereby lawmakers from opposing parties agree that one will abstain from voting due to the planned absence of the other -- for reasons of illness, travel, or other legitimate commitments. (It's not foolproof in the West, but tends to work well and you'd have to go back nearly a century to find a major example of its failure.)
But nothing is easy on the fractious Ukrainian political landscape, where brawls have broken out on at least two occasions (in December and May) in the past year alone.
Klitschko, who is almost 2 meters tall and boasts a professional record of 47-2 (45 of those wins by knockout), has vowed that the podium will remain blocked until his alliance's demands have been met -- even if that means early elections.
The standoff comes just three months after national elections to fill the current parliament (with the exception of five contested races). February 5 marked the first day back for the legislature since the winter break.
Ukrainian President Viktor Yanukovych could dissolve parliament if it fails to conduct any business for 30 days or more.
But the standoff could prove hugely embarrassing if it lasts even another day, with visiting European Union Enlargement Commissioner Stefan Fuele scheduled to address the Ukrainian parliament on February 7.
Kyiv's perceived backsliding on the rule of law has already cost it dearly in Brussels.
Ukrainian officials were hoping a EU-Ukraine summit on February 25 would break an impasse over trade agreements put on hold by the EU over the jailing of Yanukovych foe and former Prime Minister Yulia Tymoshenko, who is already serving a seven-year sentence and has reportedly been informed she could face murder charges.
-- Andy Heil