KYIV (Reuters) - Ukrainian President Viktor Yushchenko's chief of staff, a figure who had long exerted considerable influence over the former Soviet republic's leader, has tendered his resignation, Ukrainian media report.
The Internet news service Ukrainska Pravda quoted chief of staff Viktor Baloha as saying he had submitted his resignation about a month ago, but gave no reason for the move. He said he was currently on leave.
Yushchenko's office was unavailable for comment.
Television stations also reported Baloha's offer to resign, quoting him as saying it was up to the president to decide on the matter.
State television quoted a source in Yushchenko's office as saying the president had accepted Baloha's resignation and replaced him with a senior civil servant, Ihor Tarasyuk.
Baloha had until recent months wielded great influence in Yushchenko's office, spearheading attacks on Prime Minister Yulia Tymoshenko -- the president's estranged ally from the 2004 Orange Revolution that swept pro-Western leaders to power.
He had more recently been less prominent in his public statements.
Since Yushchenko came to power on the back of weeks of "orange" mass rallies against fraud in a presidential election, Ukraine has been almost constantly gripped by infighting among its leaders.
As politicians gear up for the next presidential poll, Yushchenko's popularity has sunk to single figures -- far behind opposition leader Viktor Yanukovych, the man he defeated in the rerun of the rigged 2004 contest, and Tymoshenko.
Ukraine's Constitutional Court this week struck down the October 25 date set by parliament for the presidential election, and the chamber must now choose a new date -- probably early in 2010, as long suggested by many senior politicians.