Last year, Ukraine saw a shift from the presidential-parliamentary to parliamentary-presidential form of governance, with some presidential powers transferred to parliament, the Supreme Rada.
"Ukraine has a president elected by popular vote, and I was opposed to stripping him of his powers. Today, I am working hard to return the president his powers so that he is able to do all he was supposed to do following the 'orange revolution'," Tymoshenko said at a meeting with members of the Ukrainian community in Washington.
The Supreme Rada approved the law December 8, 2004, during the 'orange revolution', which brought Western-leaning leader Viktor Yushchenko to the presidency and secured the prime ministerial post for Tymoshenko.
Tymoshenko backed the law at the time, when she was opposed to the incumbent Russia-oriented President Leonid Kuchma.
The female prime minister was Yushchenko's close ally until being discharged following a public falling out.
She has been seeking to reinstate herself as prime minister ever since, but failed to form an 'orange' coalition following parliamentary elections last March, being outstripped by Viktor Yanukovych, leader of the pro-Russian Party of Regions and her arch-enemy, who formed a new coalition ending months of political crisis in the country and became head of the government.
In a follow-up to the constitutional amendments, a law came into effect in February allowing a parliamentary majority to nominate the prime minister and Cabinet ministers.
The law had repeatedly but unsuccessfully been vetoed by President Yushchenko, with the parliament overriding the vetoes.
Justice Minister Oleksandr Lavrynovych voiced his concerns Friday over what he said was a menacing trend for the president to veto parliamentary bills.
He said the president has vetoed 26 laws of 140 approved by the Supreme Rada since last August, and 13 of 20 approved this year.
"The trend is more than menacing," the minister said, citing the example of Western countries, where he said the presidential right of veto was used three or four times in France, four times in Lithuania and not a single time in Slovakia last year.