While it's easy to find the US Senate voting records for these NATO expansion treaties, it's been surprising hard (for me) to find much about parliamentary ratification of those expansions in European countries (including Turkey).
One can find some information about the executive-level disagreements at the 1997 Madrid conference, for instance (where some European countries, in particularly France, were arguing about a more expansive 1st wave, contra Washington.) And I've seen briefly mentioned that the cohabitation government in France in 1997 made it more difficult for the measure to pass, but not stated in any numerical terms. Likewise, I've seen mentioned that the French and German governments were not exactly pleased with 2004-wave candidates effectively siding with the US on the invasion of Iraq. (The French government publically berated the "Vilinius Ten".) But I've not seen what this meant in terms of parliamentary approval in those two countries for the 2004 expansion.
So, in which country (that requires parliamentary ratification of such matters) did the 1999 & 2004 NATO expansions prove most controversial in numerical terms, i.e. received least percentage of votes?
(N.B. NATO has a the dates of parliamentary ratifications by country, at least for the 2004 wave, so that might be a starting point, but it doesn't give complete numerical votes in favor. It does mention that in a number of countries there were zero or only handful of votes against, and in which countries that happened, but I have the slight feeling that info might be a bit "cherry picked". But at least it reduces the search/work to the rest...)