Ukraine is headed for a constitutional crisis similar to Russian president Boris Yeltsin’s showdown with the communist-dominated Duma in 1993, if Ukraine’s President Petro Poroshenko plays his cards badly in his stand-off with former Odesa governor and ex-Georgian president Mikheil Saakashvili, who is proposing to hold a series of regional rallies attacking the president.

Saakashvili was literally dragged across the Polish-Ukrainian border by his supporters at the weekend without a valid passport, after Poroshenko revoked his citizenship earlier this year.

He is now threatening to hold a national tour of the country — in the style of those organised by Russian opposition leader Alexey Navalny — to lambast the president before marching on Kyiv. While he says that he will not stand in the upcoming presidential elections in 2019, he has thrown his support behind opposition leader, former prime minister and head of the Batkivshchyna (Fatherland) party Yulia Tymoshenko, who will challenge Poroshenko in the elections.

Tymoshenko is back from the political dead and she and her party are currently leading the polls for both parliamentary and presidential elections with 10% and 11% of the vote respectively. Poroshenko, on the other hand, is weak and his personal popularity is under 2%, according to some polls. This leaves him exposed to both Russian interference and an attack from the Saakashvili-Tymoshenko duo.

As bne IntelliNews columnist and Ukrainian political activist Kateryna Kruk has pointed out in her Kruk Report column, Poroshenko is already playing dirty ahead of the elections. On the other hand, the whole circus playing out in Lviv, where Saakashvili is currently based, has been condemned by the average Ukrainian, who is fed up with the dogfighting amongst the political elite. They would prefer that the government gets on with the job of reforming the country and increasing prosperity for everyone.

Saakashvili’s actions are not only a clear affront to Poroshenko’s power, but they also undermine the rule of law. The sight of a leading politician illegally crossing the border through the use of force is reminiscent of the clash between Yeltsin and the Duma in 1993 that ended in bloodshed and tanks on the streets of Moscow. In that fight the president and the Duma, where the power actually lies according to Russia’s constitution, were at loggerheads. Yeltsin chose to illegally disband the Duma and after he won the three-day long street battles that saw an estimated 2,000 people killed by snipers, and changed the constitution in his favour.

So far Poroshenko has been cautious about using violence. Although a platoon of border guards linked arms and physically resisted Saakashvili’s crossing into Ukraine before being overwhelmed by the crowd, they were specifically ordered not to use weapons, according to a Facebook post by boarder guard officer Oleh Slobodian.

Saakashvili is operating outside the law, but is banking on Poroshenko’s extremely low popularity ratings, and by going to the streets in a series of rallies is challenging Poroshenko to act. The knee jerk reaction would be to simply uphold the law and arrest Saakashvili, which Poroshenko would be within his rights to do. But clearly the muted violence at the Polish-Ukrainian border suggests arresting Saakashvili could spark wider violence and start a third Maidan protest.

The main difference between Ukraine today and Russia in 1993 is that the latter was a showdown between the two constitutional centres of power: the president and the parliament. In this case Saakashvili is not a member of parliament nor even Ukrainian-born. Moreover, his political party, the New Forces Movement, also polls very low in Ukraine.

Against that, Tymoshenko’s decision to closely ally with Saakashvili is a lot more ominous as she is both a member of parliament and the frontrunner in the polls – albeit with a surprisingly low approval rating given how unpopular Poroshenko is; the recent polls highlighted that in reality the Ukrainian people are unhappy with all their political leaders, not just Poroshenko. “Won't vote” scored almost twice as many responses in the recent poll as Tymoshenko did.

Still, Tymoshenko has her Orange Revolution credentials from the first Maidan protest, where she stood on the barricades. But her position has been weakened by the crowd’s manifest rejection of her at the end of the second EuroMaidan protests that ousted former president Viktor Yanukovych from office four years ago.

In the meantime the tension is rising. The Ukrainian prosecutor's office said it is looking into a request by its Georgian counterpart for the extradition of Saakashvili, who is wanted in his birth-country on corruption charges.

"After receiving this request [from the Georgian side for extradition], all materials were sent to the prosecutor's office for an extradition check. This is a preliminary stage. If it [the verification] is completed with a positive conclusion, then it will be possible to take further procedural decisions in strict accordance with the law," Justice Minister Pavlo Petrenko said at a briefing in Kyiv on August 12, reports Interfax.

The Ministry of Internal Affairs of Ukraine also said it believes that Saakashvili's presence in Ukraine is illegal, but added there are not sufficient grounds for his detention. So far the government has limited itself to issuing a protocol for an administrative offence to Saakashvili, along with 14 other individuals. Five people have been arrested for using violence against the border guards during Saakashvili’s crossing on September 10.

In the meantime Saakashvili is milking the media circus that follows him around for all it’s worth. He issued a colourful statement after police officers came to his hotel in Lviv on August 12 to serve the administrative order to appear at a local court and told him his Ukrainian passport was in the president’s office.

"I am declaring officially that the passport that was stolen from me, based on information that I received from very, very well-informed sources, it is currently at the office of Ukrainian President Petro Oleksiyovych Poroshenko. My passport was brought to him in the morning, when he came to work after our return to Ukraine. This is information that I possess now," Saakashvili said according to Interfax.

The action taken against Tymoshenko for crossing the border alongside Saakashvili has also been muted so far. The worst that has happened is her name has been added to the Ukrainian website Myrotvorets, a database that records the names of people it deems are a threat to Ukraine's sovereignty.

"The illegal crossing of Ukraine's state border. An assault within a group of persons on border guards fulfilling their duties to protect the state border of Ukraine. Participation in preparations for the illegal crossing of Ukraine's border by a person without Ukrainian citizenship. Manipulation of socially important information," the Myrotvorets website says.