Questions over Greece's ability to meet the terms of its first rescue package are dogging the indebted nation as bondholders weigh whether to participate in a debt exchange that's crucial to a second bailout.

Greece is seeking preliminary responses today from bond investors to the proposed debt swap, part of a 159 billion-euro ($220 billion) European Union rescue plan agreed upon in July. Responses to the inquiry, which is not a formal offer, are nonbinding and will be aggregated by regulators on a country-by-country basis, according to the Greek government.

"We do not expect any official announcement today or in the coming days regarding the investor submissions and level of expected participation," analysts at Barclays Capital wrote in a research note. The analysts said that even if there are indications of high interest, "we would see no reason for the authorities to reveal the fact in order to keep the incentives at play to minimize holdouts."