BRUSSELS -- The European Commission says corruption and press freedom limitations are undermining the European Union membership bids of Montenegro and Serbia.
The assessments are from the commission's October 8 enlargement report on progress by candidate countries.
The report says Montenegro is the Western Balkan candidate that is closest to joining the EU.
But it warns negotiations will slow down unless Montenegro makes more progress on judicial reforms.
The report says Serbia has shown "a big political impetus to fight corruption" since opening EU accession negotiations in January.
But Brussels says Belgrade must ensure an independent judiciary and fight corruption that is "still is prevalent in many areas."
The report adds that Belgrade's plans to build a portion of the South Stream pipeline for Russian natural gas, as well as its refusal to follow the EU's lead on sanctions against Russia over the Ukraine crisis, could also cause problems for Belgrade's EU membership bid.
But the report's biggest criticism about Serbia is related to the media environment, where the "freedom of expression has deteriorated, particularly in the first half of 2014" with a growing trend of self-censorship and undue influences on editorial policies.
The report says Bosnia-Herzegovina "remains at a standstill" on establishing functional institutions.
The list of complaints against Bosnia is long -- including weak cooperation with civil society by all levels of government and little progress toward make the country a fully functional market economy.
It also warns that political patronage networks are widespread and influence all levels of government -- with little political will to move beyond rhetoric and actually implement judicial reforms and tackle the problems of organized crime and corruption.
Kosovo is seen as being the furthest down in the pecking order out of all the Western Balkans countries that hope to join the EU.
The EU report notes that Kosovo also suffers from widespread corruption and a lack of judicial independence.
It says the need to implement the rule of law in Kosovo, as well as limited progress in the fight against organized crime and corruption, remain major concerns.
It is also critical of the fact that a government has not yet been formed since elections in June.
According to the report, "the failure to constitute the new legislature smoothly and in a timely manner has been a setback."
The report notes that Macedonia has been an EU candidate country since 2005, but Skopje continues to face opposition from Greece on the question of starting formal EU accession talks due to its dispute with Greece over the name "Macedonia."
It says the name dispute is having "a direct and adverse impact on the country's European aspirations."
The report is the last under the current European Commission.
With new politicians who are taking charge in Brussels next month indicating that there will not be any expansion during their five-year-mandate, questions are being raised about the influence of the EU in the Western Balkans.