Though he's not known for his deep knowledge of American political history, with his approval ratings languishing in the mid-30s, President Trump could be excused if his thoughts occasionally turn to the last time an incumbent president faced a serious challenge to his renomination.

That contest --- the 1980 Democratic nomination fight between President Jimmy Carter and Massachusetts Senator Edward Kennedy --- is the subject of Yahoo News senior political correspondent Jon Ward's CAMELOT'S END: Kennedy vs. Carter and the Fight that Broke the Democratic Party. Ward's book is a capable account of the ultimately quixotic effort by the last of the Kennedy brothers to fulfill his family's destiny and achieve personal redemption.

In brief biographical sketches, Ward describes how the circumstances that brought Carter and Kennedy to the pinnacle of American politics couldn't have differed more starkly. Contrary to his image as a soft-spoken Sunday school teacher from a small Georgia town, Carter was a "determined and competitive politician" whose rapid ascent to the presidency was propelled by less than subtle appeals to racism in his 1970 campaign for governor of Georgia. Kennedy was the heir to a family of American political royalty, his appeal enhanced by the twin tragedies of his brothers' assassinations.

"...a capable account of the ultimately quixotic effort by the last of the Kennedy brothers to fulfill his family's destiny and achieve personal redemption."

Almost from the moment that his brother Robert's 1968 presidential campaign was cut short, Kennedy's ardent supporters longed for the day he would be a Democratic presidential nominee. But in July 1969, his involvement in an automobile accident on Chappaquiddick Island that killed Mary Jo Kopechne appeared to have brought an end to their hopes, and his ambitions, vague though they were at times. Even with that, Kennedy flirted with the possibility of a run in both 1972 and 1976. By the fall of 1979, however, frustrated with what he saw as Carter's lackluster leadership, particularly on the issue of healthcare, and buoyed by polls showing him leading the incumbent by 2 to 1, he finally decided to mount the challenge.

As Ward describes it, Kennedy, "driven by forces larger than himself," ran what often seemed at best a halfhearted campaign, doomed both by his ineffectiveness as a candidate and by the superiority of the Carter campaign's effort at amassing an insurmountable lead in the delegate count, even without dominating the primary vote in key states. Twin foreign policy crises in late 1979 --- the seizure of 66 American hostages at the US Embassy in Iran and the Soviet invasion of Afghanistan --- paradoxically boosted Carter's popularity, and his decision to confine his campaigning to the Rose Garden mostly blunted the effectiveness of Kennedy's attacks. Kennedy, in Ward's epitaph for the campaign, had been "lured into a presidential run by an inviting set of circumstances, only to see the landscape shift dramatically," and the result was the most consequential electoral defeat for any member of the family.

Unsurprisingly, the Kennedy campaign's last-minute effort to force an open convention fizzled, but he rallied from that fiasco to deliver a rousing speech to the delegates that is still considered by many a masterpiece of political oratory. The awkward drama on the convention stage on the night of Carter's nomination, when Kennedy refused to pose for the traditional hands-raised photograph (Ward hints at reports he may have been intoxicated), provided a fitting end to the sour race.

For all of Ward's skill in bringing to life the events of the nomination contest, he's less effective in advancing his thesis that Kennedy's challenge "broke" the Democratic Party and, ultimately, accounted for Carter's defeat. It's impossible to know what the outcome of the general election would have been had Carter traveled a smooth path to the nomination. But he ran in the face of strong political headwinds against an opponent, Ronald Reagan, whose affable personality and simple vision for America offered a sharp contrast to the grim prospect of rising inflation, gas shortages and an ineffective foreign policy (symbolized most dramatically in the disastrous effort to rescue the Iran hostages in April 1980) that dogged Carter's presidency. Reagan succeeded where Kennedy failed, crafting an optimistic message that energized Republicans and peeled off disgruntled traditional Democratic voters to build a coalition that won him a decisive popular vote win and a massive Electoral College majority.

As Ward succinctly explains in his book's concluding chapter, the irony of the Kennedy-Carter battle is that both of the principals rebounded from devastating political defeats in second acts that surpassed anything either achieved earlier in his career. In his post-presidency, Carter devoted himself to an array of charitable activities, while producing more than 30 books. His leadership in the fight for human rights won him the Nobel Peace Prize in 2002. At age 94, nearly four years after a cancer diagnosis, he remains a vigorous advocate for a variety of causes.

Kennedy went on to serve another 29 years in the Senate, becoming what Ward calls "a model of what an effective senator could be." He died in August 2009, as the fourth-longest-serving senator in history, and just a few months before the passage of the Affordable Care Act, the closest the country has come to achieving his lifelong goal of universal healthcare.

The 2020 presidential election is still 21 months away. For all the activity among the Democratic aspirants, the rumors of a Republican challenger have remained just that. Should one arise, CAMELOT'S END will be a useful book to pull down from the shelf.