The top U.S. diplomat for African affairs, Johnnie Carson, will go to Nigeria to observe parliamentary elections scheduled for Saturday.
Nigeria delayed the polls by a week following widespread logistical problems on the initial election day April 2. The delay also forced postponements to the presidential and state governor elections.
In remarks this week, Carson said the United States is disappointed that Nigeria postponed the polls.
He said Nigerians will lose confidence in their leaders and the country's ability to move toward democracy if this year's elections are not significantly better than the last ones in 2007.
Those elections were marked by widespread violence, fraud and organizational chaos, prompting the European Union to declare them "not credible." Legal challenges to the results dragged on for months.
Nigeria's electoral commission has expressed optimism it will hold the parliamentary polls on Saturday. But the commission has not ruled out the possibility of another postponement.
The delay this week sparked accusations that the ruling People's Democratic Party sabotaged the polls. The PDP has rejected the allegations.
Under the current schedule, the parliamentary polls will be followed by the presidential vote April 16 and state-level polls on April 26.
U.S. diplomat Carson is due to arrive in Nigeria Friday.
Some information for this report was provided by AP, AFP and Reuters.