The release of Tymoshenko, who is serving a seven-year jail sentence on abuse of power, is seen as a prerequisite for Ukraine's signing landmark deals with the European Union next month.
The EU views Tymoshenko’s imprisonment as a case of “selective justice" and demands her release before the summit on November 28-29 in Vilnius.
“It all depends on the President of Ukraine, because [the president] has absolute power in our country,” Klichko said.
“If Viktor Yanukovych wants to do it, Yulia Tymoshenko will be free tomorrow.”
But “I have a bad feeling” about that, Klichko added.
Klichko, who currently has the best chance of beating Yanukovych at the next election in March 2015, called on the president to approve a historic decision that would lead to the signing of the deals and would benefit 46 million of Ukrainians.
“I hope that Yanukovych will take a very important decision - not for himself, but for the 46 million people across the country,” Klichko said.
The call come less than a week after two European Union ministers urged Ukraine to stop "bluffing" and reach a deal on the release of Tymoshenko because time was running out.
Polish Foreign Minister Radoslaw Sikorski and Sweden's Carl Bildt met Yanukovych amid a flurry of diplomatic activity aimed at nailing down a compromise on the Tymoshenko row.
Her case has become symbolic for the EU of "selective justice" which the bloc wants ended in the former Soviet republic before agreements on association and free trade are signed in Vilnius.
Yanukovych is seen as being anxious at keeping Tymoshenko out of action as a political force as he prepares for the run-up to a re-election bid in 2015 and has stalled over releasing her.
Yanukovych said recently he would sign a law to allow her to go to Germany for medical treatment for spinal problems, if such a draft were adopted by Parliament.
But he has balked at a call by European mediators to pardon her and wipe out her sentence altogether - something which opposition supporters of Tymoshenko are still asking for.
Drafts of possible legislation floated by pro-Yanukovych deputies envisage her going to Germany only as a convicted criminal and returning to Ukraine to complete her sentence after treatment.
Source: Ukrainian Journal