President Barack Obama says he thinks Hillary Rodham Clinton would be "an excellent president."
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Clinton is expected to launch her long-anticipated second run for president on Sunday with an online video.
Obama says Clinton was a formidable candidate against him when they competed for the Democratic nomination in 2008.
He says she became a great supporter of his in the general election that year, and that she was an outstanding secretary of state during his first term.
Says Obama: "I think she would be an excellent president."
He adds that Clinton will have strong messages to deliver if she does decide to run.
Clinton's presidential campaign will center on boosting economic security for the middle class and expanding opportunities for working families, while casting the former senator and secretary of state as a "tenacious fighter" able to get results, two senior advisers said Saturday.
The senior advisers provided the first preview of the message Clinton planned to convey when she launches her long-anticipated campaign on Sunday with an online video. Until now, the former first lady has offered only hints of what would drive her if she were to run a second time for the White House.
The strategy described by Clinton's advisers has echoes of Obama's 2012 re-election campaign. He framed the choice for voters as between Democrats focused on the middle class and Republicans wanting to protect the wealthy and return to policies that led to the 2008 economic collapse.
The advisers said Clinton will argue that voters have a similar choice in 2016. Clinton also intends to sell herself as being able to work with Congress, businesses and world leaders.
That approach could be perceived as a critique of Obama, Clinton's rival for the nomination in 2008. He has largely been unable to fulfill his pledge to end Washington's intense partisanship and found much of his presidency stymied by gridlock with Congress.
The Clinton advisers spoke on condition of anonymity in order to discuss her plans ahead of Sunday's announcement. People familiar with the plans say Clinton will travel to Iowa and other early-voting states to hold small events with residents in the days after the video's release.
In New York on Saturday, at the final event put on by "Ready for Hillary," a group not connected with her campaign that's worked for the past few years to stoke excitement for it, enthusiastic supporters joined elected officials and local party leaders to celebrate the launch to come.
"After she left the State Department she could have slipped into grandmother-hood, but people want to call her back into public service," said Jarret Berg, 29, a Democratic staffer in the New York legislature. "It's time for her."
As her official announcement loomed, the Republican National Committee linked Clinton to Obama, a regular focus of criticism from the GOP. "All Hillary Clinton is offering is a continuation of the same big government ideas that have grown Washington instead of the middle class," RNC spokesman Michael Short said in a statement. "That's why voters want fresh leadership and a new direction, not four more years of Obama's failed policies."
Clinton is not expected to roll out detailed policy positions in the first weeks of her campaign. Advisers said she planned to talk about ways families can increase take-home pay, the importance of expanding early childhood education and making higher education more affordable.
It's not yet clear whether that will include a noticeable break with Obama on economic policy. The GOP has hammered Obama's approach as anti-business and insufficient in the wake of the recession. The White House says the economy has improved significantly in recent years.
The unemployment rate fell to 5.5 percent in March, but manufacturing and new home construction slowed, cheaper gas has yet to ignite consumer spending and participation in the labor force remains sluggish.
Clinton will enter the race as the overwhelming favorite for her party's nomination. Still, her team has said her early strategy is designed to avoid appearing to take that nomination for granted.
Clinton received an early boost Saturday from Obama, who was asked if he would be involved in her expected campaign.
"She was a formidable candidate in 2008. She was a great supporter of mine in the general election. She was an outstanding secretary of state. She is my friend. I think she would be an excellent president, and I'm not on the ballot so I'm not going to step on her lines," Obama said from Panama City as he wrapped up participation in a summit of Western Hemisphere leaders.