WASHINGTON — Chuck Hagel, the former US senator believed to be President Obama’s top choice for defense secretary, apologized Friday for remarks he made in 1998 on an openly gay nominee for an ambassadorship.

In a brief written statement, the Republican said his comments about James C. Hormel were ‘‘insensitive’’ and did not reflect his views ‘‘or the totality of my public record.’’ The Vietnam veteran served two terms in the Senate, retiring in 2009.