Responding to the controversy surrounding a newly published remark he made privately about Obama's race in 2008, Reid sought to emphasize his long-standing support for the nation's first African-American president.
"I can still remember the meeting that took place in my office with Sen. Barack Obama, telling him that I think he can be elected president," Reid said.
Obama "was kind of surprised that the Democratic leader was calling this new senator over to suggest that he could be elected president," he added.
He said numerous prominent African-American officials, including NAACP Chairman Julian Bond and Attorney General Eric Holder, have called him to offer support in the wake of the controversy that began on the weekend.
"I've apologized to everyone with the sound of my voice that I could have used a better choice of words," he told reporters after an event announcing a new energy project in his home state. "And I'll continue doing my work for the African-American community."
Reid said that "as as very young man" he became a leader of civil rights efforts, including the integration of the gaming community.
He added that Interior Secretary Ken Salazar called him to say he should "tell everybody that you have done more for diversity in the United States Senate than all the rest of the people put together."
Asked whether he should apologize to voters, Reid - who had issued a statement over the weekend apologizing "for offending any and all Americans" - did not answer directly and instead cited the support he has received from around the country and within his own state.
"I'm not going to dwell on this any more," Reid said. "It's in the book. I've made all the statements I'm going to make."
The book he referred to, "Game Change," went on sale Monday.
Looking at the 2008 presidential race, it recounts a moment in which Reid said privately that Obama could succeed as a black candidate partly because of his "light-skinned" appearance and his speaking patterns "with no Negro dialect, unless he wanted to have one."
The authors write that "Reid was convinced, in fact, that Obama's race would help him more than hurt him in a bid for the Democratic nomination."
Reid apologized in a statement sent to CNN on the weekend. "I deeply regret using such a poor choice of words," he said.
He added, "I sincerely apologize for offending any and all Americans, especially African-Americans, for my improper comments. I was a proud and enthusiastic supporter of Barack Obama during the campaign and have worked as hard as I can to advance President Obama's legislative agenda."
Reid called the president Saturday and apologized. After the call, Obama expressed support for Reid and said, "As far as I am concerned, the book is closed."
"I accepted Harry's apology without question, because I've known him for years. I've seen the passionate leadership he's shown on issues of social justice and I know what's in his heart," the president said.
Reid also called a host of African-American political figures, including House Democrats Barbara Lee of California and Jim Clyburn of South Carolina; the Rev. Al Sharpton; CNN political contributor and Democratic strategist Donna Brazile; and the head of the Leadership Conference on Civil Rights, Wade
Republicans pounced on the controversy.
Sen. John Cornyn, R-Texas, head of the GOP's Senate campaign arm, called for Reid to give up his leadership posts following the "embarrassing and racially insensitive" remarks.
Republican Party Chairman Michael Steele, speaking Sunday to NBC's "Meet the Press," also called for Reid to step down. "Racism and racist conversations have no place today in America," said the first African-American GOP chairman.
Steele was also on the defensive, for a remark he made last week.
Speaking to Fox News, Steele said the GOP platform "is one of the best political documents that's been written in the last 25 years, 'honest Injun' on that."
"Fox News Sunday" host Chris Wallace noted that lawmakers from both parties have called that a racial slur.
"Well, if it is, I apologize for it. It's not an intent to be a racial slur. I wasn't intending to say a racial slur at all," Steele said.
Numerous Democrats came to Reid's defense. The Congressional Black Caucus said Sunday that it had accepted his apology and dismissed calls for the Nevada Democrat to step down.
"Senator Reid's record provides a stark contrast to actions of Republicans to block legislation that would benefit poor and minority communities," Lee, chairwoman of the caucus, said in a written statement.
Rep. Eleanor Holmes Norton, D-District of Columbia, a former chairwoman of the Equal Employment Opportunity Commission, issued a statement saying, "Like President Barack Obama, African-Americans are likely to accept Majority Leader Reid's apology for an obvious reason. He has earned it."
She added, "Harry Reid's opponents will not find a welcome mat in the black community if they seek to capitalize on the Reid remark. While Sen. Reid has been producing for African-Americans, many of his critics were opposing him on these same issues."
Democrats rejected a parallel drawn by some Republicans between Reid's remark and one by former Senator Trent Lott, R-Mississippi, in 2002. Lott lost his post as Senate majority leader after saying the nation would have been better off if Strom Thurmond had been elected president when he ran as a segregationist candidate in 1948.
"There is a big double standard here," Steele said on NBC. "When Democrats get caught saying racist things, you know, an apology is enough."
Gov. Tim Kaine of Virginia, chairman of the Democratic Party, shot back, telling NBC "there is no comparison" between the two sets of remarks.
Reid is embroiled in a tough re-election campaign to stay in the Senate at all. Only one-third of Nevada voters have a favorable opinion of him, while 52 percent have an unfavorable opinion of the four-term senator, according to a survey by Mason-Dixon Polling and Research for the Last Vegas Review-Journal released over the weekend.
The poll was conducted Tuesday through Thursday, before news of Reid's comments.
Updated: 3:49 p.m.
–CNN's Dana Bash, Mark Preston, Rebecca Sinderbrand, and Paul Steinhauser contributed to this report.