In Kiev ahead of a NATO summit, the president said he would work ''as hard as I can'' to overcome Moscow's objections and concerns from some in the trans-Atlantic military alliance about starting the admission process for the two nations.

''Your nation has made a bold decision and the United States strongly supports your request,'' Bush told Ukrainian President Viktor Yushchenko two days before NATO leaders meet in Bucharest, Romania to decide on a so-called ''membership action plan,'' or MAP, for both Ukraine and Georgia.

''In Bucharest this week, I will continue to make America's position clear: we support MAP for Ukraine and Georgia,'' he said after talks with Yushchenko. ''My stop here should be a clear signal to everybody that I mean what I say: It's in our interest for Ukraine to join.''

A membership action plan outlines what a country needs to do to win an invitation for full NATO membership.

With nine former Soviet bloc countries already NATO members, Russia is opposed to Ukraine and Georgia even starting the process, fearing a further loss of influence in two more Soviet-era Warsaw Pact neighbors. A senior Russian diplomat warned Tuesday that Ukraine's accession to NATO would cause a ''deep crisis'' in relations with Moscow.

Some NATO allies, notably France and Germany, are reluctant to give Ukraine and Georgia the precursor to membership, saying they are not ready. But they also fear upsetting already strained ties with Russia, a major supplier of energy to Europe.
But Bush praised Ukraine's democratic and military reforms, and noted that Ukraine ''is the only non-NATO nation supporting every NATO mission.'' Ukraine has sent troops to Afghanistan, Kosovo and Iraq. He said a positive decision is ''in the interests of our organization.''

Bush's forceful backing sets up an internal showdown in the alliance. The president said he and his top aides would continue to lobby all NATO members.

''Every nation has told me Russia will not have a veto over what happens in Bucharest. I take their word for it,'' he said, adding: ''I wouldn't prejudge the outcome just yet, the vote will be taken in Bucharest.''

The pro-western Yushchenko said he was optimistic his country would get the nod from NATO and discounted opposition from some in Ukraine to moving to join the alliance.

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