President Barack Obama's approval ratings are up, and he seems more willing than ever to make waves and push for his policies until Election Day and beyond.

This is good news for Hillary Clinton, who got another lift Tuesday by winning four major state primaries, in Florida, Illinois, North Carolina and Ohio, and expanding her delegate lead to about half of what she needs to reach a majority and clinch the Democratic presidential nomination.

As his former secretary of state and the Democratic front-runner, Clinton has been embracing Obama's agenda and running as his political heir. She differs with him on some issues, such as immigration, where she recently said that as president she would not deport people who entered the United States illegally as long as they didn't have a criminal record after they got here. Obama hasn't gone that far, but he has been seen by many Latinos as more supportive of their views on immigration and generally more welcoming of immigrants than the Republican presidential candidates. So in this sense, Clinton is continuing in Obama's footsteps by appealing to Latinos as an essential part of her coalition, just as Obama did in winning huge majorities of Latino voters in his successful presidential campaigns of 2008 and 2012.

Clinton, in her speeches, media interviews and debate performances, has tethered herself tightly to Obama. She portrays him as an excellent president who has improved the economy, helped to create jobs and adopted common-sense policies on many issues from health care reform to improving education and backing massive federal investments in infrastructure.

The rise of Obama's approval ratings, although it has been modest, is likely to help Clinton. If a two-term incumbent's popularity is strong, this tends to help the incumbent party's next presidential nominee. And even though it's difficult for an incumbent party to win the presidency more than twice in a row, it can be done, as Republican George H.W. Bush showed when he won the White House as Ronald Reagan's heir in 1988 after Reagan's two terms. Since then, the incumbent party has been thrown out of the White House after two terms. It happened in 2000 when Republican George W. Bush, the former president's son, succeeded two-term Democrat Bill Clinton, and again in 2008 when Democrat Obama succeeded two-term President Bush.

Today Obama must look especially good to many voters – steady, careful, dignified, statesmanlike – compared with the petulant and combative Republicans trying to replace him, which probably accounts for a good portion of Obama's rise to 50 percent job approval. This is his highest poll rating since May 2013, according to Gallup, and higher than the average 47 percent approval he has received since he took office in 2009. (Obama's 50 percent job approval is comparable to Ronald Reagan's 51 percent in March of 1988, his final year in office. Bill Clinton's rating in March 2000 was 63 percent, and George W. Bush's was 32 percent).

"There's a sense that the presidential candidates are not palatable to a lot of the public," Art Swift, managing editor at Gallup, told Yahoo Politics. "And I think people are starting to realize they had a pretty good deal with President Obama. They understand him. They know him. I'm sure there's more fondness for him than people even realize."

Obama has a few more statesmanlike moments coming up such as when he visits Cuba March 20-22 under his new normalization policy. He also showed discretion this week when he selected federal appeals court judge Merrick Garland to replace the late Antonin Scalia on the Supreme Court. Garland is a left-of-center moderate who isn't known as an ideologue. But majority Republicans in the Senate say they will block this nomination so the next president can decide the direction of the court with a new justice. Many voters will see this dynamic as more evidence that the GOP is obstructionist and too stubborn to govern properly.

The contrast between Obama and the GOP will grow more stark if Republican front-runner Donald Trump continues his march to the Republican presidential nomination, riding a wave of insults toward opposition groups and individuals, relying on one-liners reminiscent of a reality television show (in which Trump once starred as host of "The Apprentice"), exploiting the anger of key segments of the electorate. Obama's policies might have divided the country, but the level of animosity stirred up by Trump appears to be much worse, encouraging at least some Americans to see Obama more favorably.

Clinton has her own problems. Many voters don't trust her and consider the former first lady a politician of the past. But Obama's improved ratings may help Clinton because, pollsters say, an incumbent president's approval rating can be a strong signal of how the voters will evaluate his would-be successor of the same party in the next general election.