"I hear that the overall reaction (in Nato) is positive, that there is no objection to this," Ukraine's Nato ambassador Volodymyr Khandogiy told Reuters.
Nato sources said a final decision to invite Yushchenko could come on Thursday. "The (Nato) nations are inclined to say yes," one said.
Nato cancelled a ministerial meeting with Ukraine in December over the rigging of the presidential election in which pro-Russian Prime Minister Viktor Yanukovich initially claimed victory. The ballot was re-run and Yushchenko won.