Sidney Blumenthal describes Abraham Lincoln as a masterful politician confronting the key issue of his time: slavery. (Jonathan Newton/WASHINGTON POST)

Michael Green is an associate professor of history at the University of Nevada, Las Vegas, and the author of several books on the Civil War era, including “Lincoln and the Election of 1860,” and on Nevada history.

It was no small feat that Abraham Lincoln was able to maneuver his reelection in 1864. The last president to win a second term, Andrew Jackson, did so in 1832 with his party united and without the weight of a a bloody, three-year-old war. Lincoln was, in the words of Doris Kearns Goodwin and others, a “political genius.”

Sidney Blumenthal would agree. Blumenthal, a longtime journalist who worked for a president who won two terms, believes that Lincoln accomplished what he did because he was a politician from his toenails to the top of his stovepipe hat. How Lincoln balanced politics and principle is central to “Wrestling With His Angel,” the second of Blumenthal’s projected four volumes on Lincoln’s political career. It follows last year’s “A Self-Made Man,” which examined Lincoln’s first 40 years.

In that volume, Lincoln was a mostly a local politician who tried to stick to his party’s principles while broadening its appeal, as Blumenthal’s former boss Bill Clinton sought to do in the Democratic Party of the 1990s. Lincoln’s efforts proved less successful. In 1849, he returned to Illinois as a one-term congressman, a capable lawyer and a minor cog in a creaky Whig political machine that soon disintegrated.

“Wrestling With His Angel: The Political Life of Abraham Lincoln Vol. II, 1849-1856,” by Sidney Blumenthal (SIMON AND SCHUSTER)

But just as Winston Churchill had his “wilderness years” to ready himself for bigger things, so did Lincoln. In 1860, five years after the Whig Party collapsed, Lincoln was elected president. How he emerged from that wilderness — how “he entered his wilderness years a man in pieces and emerged on the other end a coherent steady figure” — is the story Blumenthal tells with panache and understanding.

Lincoln grasped that “when the events changed he had to change to align himself with them.” As Blumenthal puts it, “The self-made man educated himself in the politics of democracy,” “apprenticed in logrolling,” studied “peculiar nuances of power that could not be commanded by fiat” and belonged to “the first American generation innovating in party organization, mass media, and public opinion.”

Blumenthal knows that world better than anyone else who has examined Lincoln. Two political figures — Sen. Albert Beveridge, an early 20th-century Progressive and biographer, and George McGovern, who carried the baggage of a PhD in history when he ran for president — have written biographies of Lincoln, but they did not focus, as Blumenthal does, on Lincoln as the political operative who also wrote editorials and financed newspapers. Blumenthal has spent his life in the interconnected worlds of politics and journalism, and it shows: He grasps that political genius in ways others could not, making Lincoln more politically plausible.

In explaining Lincoln’s transition from just another Whig to a rising Republican, Blumenthal keeps the man himself off the stage. Indeed, Lincoln was in the wings, watching and analyzing events as they unfolded. Blumenthal explains those developments and the personalities at the center of them, from the rigid and manipulative Jefferson Davis (Blumenthal clearly delights in discussing Davis’s herpes, which caused serious vision problems, and his extramarital affair with an Alabama politician’s wife) to the ceaselessly pandering Stephen Douglas, the longtime political rival whom Lincoln (and Blumenthal) disdained.

Blumenthal begins his story by explaining cholera, which ends up being crucial to Lincoln’s — and America’s — political evolution. In 1849, a cholera epidemic killed Mary Lincoln’s father, Robert Todd, requiring Lincoln to go to Kentucky for a lawsuit over his estate. At the time, Kentucky was debating a new constitution. Pro-slavery forces defeated efforts for gradual, compensated emancipation led by allies of Henry Clay, Lincoln’s “beau ideal of a statesman” and a friend of Mary’s father.

Lincoln lost the estate case to some of those pro-slavery politicians. Blumenthal’s understanding of politics leads him to the logical conclusion that losing the legal battle to those waging the political battle hardened Lincoln’s views. “Lincoln was broodingly silent but smoldering for years” about the case. “The tragic death of his father-in-law as he was attempting to preserve the old Kentucky, the aggressive triumphalism of the pro-slavery forces in destroying it, and the definitive loss of the Todd family estate to the leader of that movement, fused in Lincoln’s mind.”

President Zachary Taylor died during that same cholera epidemic in 1850. His death empowered Whigs who supported slavery or were willing to compromise on its expansion. When Clay died in 1852, Lincoln, increasingly conscious of the key issue, gave a eulogy that made the Kentuckian sound more anti-slavery than he really was. But, writing to a Kentucky lawyer shortly afterward, Lincoln privately called Clay’s view of slavery “bankrupt.”

Lincoln’s letter, Blumenthal observes, “transformed the Revolution into a slave revolt and the Declaration of Independence into a kind of Emancipation Proclamation.” Indeed, Lincoln showed signs of emancipating himself from his party’s attempts to compromise on slavery.

Ironically, Douglas enabled Lincoln to break his old shackles by brooking no compromise. In 1854, hoping to gain support from the increasingly rigid South, Douglas drove Congress to pass the Kansas-Nebraska Act, which obliterated existing limits on slavery and permitted it to extend north and west. He split the Democratic Party and prompted Northern anti-slavery men to plan a new party.

When Lincoln responded to Douglas in a speech at Peoria, Ill., in October 1854, he claimed the Founding Fathers and the Declaration of Independence on behalf of abolition. “Many had undoubtedly been spectators before at his amusing, sharp, and clever performances,” Blumenthal writes. “But it was at this moment that the perception of Lincoln altered.” Blumenthal calls it a “transfiguration,” but the politician survived. Blumenthal shows how Lincoln maneuvered himself and others toward the new Republican Party without entirely leaving the Whigs, at least at first. Still a political warhorse, Lincoln mapped campaigns that seemed to benefit others more than himself.

Lincoln once said, “I am slow to learn and slow to forget that which I have learned.” During the first half of the 1850s, he continued to learn about politics and about himself. Blumenthal guides us through what Lincoln learned and how he learned it as he wrestled with slavery and politics, and matured into someone who could find the better angels of our nature.

Wrestling With His Angel
The Political Life of Abraham Lincoln Vol. II, 1849-1856

By Sidney Blumenthal

Simon & Schuster.
581 pp. $35