Just hours before she was to talk up her husband at the Republican National Convention (search), first lady Laura Bush (search) did the morning show circuit Tuesday, telling "FOX & Friends" that she has particular admiration for the president's determination.

"He has the character and the integrity and the resolve to be president during these very difficult times," she told FOX via satellite from Dearborn, Mich. "I think the American people know that."

In fact, she has been attracted to George W. Bush's "steely resolve" since the beginning of their marriage, Laura Bush said.

"I loved his sense of humor 'cause I knew he would make me laugh, but I also loved his resolve and his ambition and his seriousness," the first lady said. "It's very important in times like we've had in the last three years in our country."

Laura Bush acknowledged that the situation in Iraq is a tough one, but she supports the president's goal to "complete the mission."

"Is it difficult? Of course. And are there many more challenges? Absolutely," she said on FOX. "But we've really come a long way."

Asked how her marriage has changed since moving into the White House, the first lady said it's only grown stronger.

"I think our relationship has gotten even better," she told FOX. "We're very, very fortunate that we had a really good, strong marriage before he became president. Our relationship has really strengthened because we've had each other during these difficult times.

"You always have opponents in politics, and it certainly doesn't need to be your spouse."

The first lady also said she will use her speech to the Republican convention, which she'll deliver Tuesday night at Madison Square Garden (search), to let Americans know more about their president and not to attack Democratic rival John Kerry (search ).

"I'm going to talk about the vantage point that I have being so close to him and what I've seen over the last four years and how important it is to re-elect him and how these times demand somebody with his personality and his resolve and his character," she said on ABC's "Good Morning America."

Before her convention speech, Bush was to address Republican women, with a joint introduction by daughters Jenna and Barbara Bush (search). The twins have only recently begun campaigning for their father.

"We really protected them in every way we could before, in every other campaign," Mrs. Bush said on NBC's "Today." "We never used them in any political ads."

The recent college graduates are taking an active role now because it is their father's last campaign, she said.

"Now that they are almost 23 years old, they really wanted to be involved," she said. "They told us that they didn't want to tell their children when they were grown up that they never worked in any of his campaigns."

Mrs. Bush has appeared beside her husband during his past campaigns, but she is now spending more time at the campaign podium than ever before.

The first lady's campaign appearances are less overtly political than her husband's. She often speaks to women's organizations, and stresses the importance of education and literacy. She usually gets in a joke about her husband being surrounded by powerful women at the office, including national security adviser Condoleezza Rice (search ), and at home.

She is an effective campaigner, perhaps more so than other popular first ladies, because she appeals to committed Republicans and coveted independent voters alike, presidential scholars said.

Carl Sferrazza Anthony (search), who has written a two-volume account of first ladies, said Laura Bush comes across as more moderate, and perhaps more complex, than her husband. Her popularity draws partly a sense that "she doesn't see things in black and white. She sees shades of gray," Anthony said.

Bush has said she does not think Roe v. Wade (search), the Supreme Court ruling allowing nationwide legalized abortion, should be overturned. She has also said she has an open mind about whether the country needs a constitutional amendment banning gay marriage, something her husband supports and which is part of the GOP platform.

"The president and I have very similar values," Bush said on CBS's "The Early Show." "Do we see eye to eye on every issue? Of course not. But do we understand each other's viewpoints? Absolutely."

FOX News' Catherine Donaldson-Evans and The Associated Press contributed to this report.