Moderates: The Vital Center of American Politics, From the Founding to Today by David Brown (2016). This is one of the few books that concentrates on the political center of the federal government. The first problem is figuring out what that means is, say 1820 verses 1960. The author seems more comfortable after the 1980's when liberal versus conservative and moderates can best be explained to current readers. Brown starts out with John Adams as a moderate between Hamilton's Federalists and Jefferson's Democratic Republicans. [Arguably, Hamilton represents one form of conservatism (emphasizing banking, merchants and manufacturing and the role of government to promote these interests, while Jefferson promotes to importance of agriculture (and doesn't seem to have a clue about banking).] Adams brought the Calvinist tradition of the Northeast with doubts about capitalist self-interest, while opposing slavery. Though much of history, it is difficult to determine what would be considered liberal or conservative (e.g., Jackson, Lincoln, or Teddy Roosevelt). In any case, it is worth considering history from this perspective and Brown presents a useful analysis.
Brown seems most comfortable in the post-Goldwater period, where modern constructs of liberals and conservatives have developed; however, that's the last quarter or so of the book. The starting point is John Adams, placing the second president between Hamilton's High Federalists (aristocratic, pro-Britain, promoting banking and new industry) and Jefferson's Democratic/Republicans (states rights, small government, support for agriculture, and implicitly slavery). The moderates in Brown's telling took middle positions, which involved whatever critical issue was involved at the time. For Adams it was saying out of war with either England or France. Presumably most moderates believed in deal making which involved flexibility and pragmatism and the expectation of compromise, such as Henry Clay's Missouri Compromise of 1820.
"Modern ideas" about liberalism can start with the progressive movements in the late 19th century, with both Democrat and Republican members and Teddy Roosevelt the best known. The height of the liberal movement in some ways is the New Deal period of FDR. Social Security and the concepts of a social safety net started here. This was expanded by the Great Society of LBJ and basically lost steam after that--stagflation, big federal deficits, and "straight-jacket" regulation put an end to that.
Conservatism can begin anytime, but let's start post-World War II, with an isolationist, anti-communist, anti-big government perspective. Senator Robert Taft (son of William Howard), who fits the bill and, lucky for the world, lost out the Eisenhower in 1952. He opposed NATO, although felt that the Soviet Union would take over much of Europe. His answer was bombing Europe. [Note to conservatives and liberals: now do you see the benefits of moderates?]
The second moderate discussed by Brown was Massachusetts Senator George Cabot, a director of the First Bank of the US and apposed Jefferson's Embargo Act of 1807 and opposed the War of 1812. Apparently. he is on the list by keeping New England from seceding from the US. He is followed by John Quincy Adams, another pragmatist identified by Arthur Schlesinger as an :"uncaring capitalist forerunner of Hoover." He was succeeded by Andrew Jackson who made major changes (patronage, vetoed the Second bank of the US, and is responsible for the "Trail of Tears). Chapter 4 is Lincoln, a relatively progressive Republican who favored such things as the trans-continental railroad, but was not an abolitionist (as were Radical Republicans). He opposed slavery but the Emancipation Proclamation was relatively pragmatic political move well after the Civil War started (Brown called him a"pragmatic unionist"). Henry Adams was the surprise choice of Chapter 5, known for his Education of Henry Adams and not politics (here he was skeptical of democracy). His brother, Samuel Francis Adams, Jr. seemed a better choice to me, but was not mentioned by Brown.
Theodore Roosevelt, Chapter 6, seems a better choice, although I would classify him as a progressive rather than a moderate. He is known for conservation, consumer protection and anti-trust, and perhaps something of an honest broker between business and labor. Roosevelt is worth the Edmund Morris three-volume biography. Taft is the next chapter, Teddy's hand-picked successor but a conservative. He was a lawyer and had a legal (regulation/contract-based, empathy irrelevant) mind-set; great for anti-trust enforcement but not the rest of the Roosevelt legacy.
Chapter 8 was on the Eisenhower era, but the focus was on Massachusetts Senator Henry Cabot Lodge, Jr. It would seem the chapter should have been Eisenhower, a president who categorically was a moderate (centrist, internationalist, favored NATO and the Marshall Plan, and started the International Highway System). However, according to Brown, Lodge is the one that got Eisenhower the Republican nomination for president over hard-line conservative Robert Taft. During the 1960's, the positions of conservatives versus liberals became more obvious with the 1964 fight between Republican Barry Goldwater and Democrat LB Johnson. Goldwater lost big, but set the stage for the future election of Ronald Reagan.
LBJ's problems (with Vietnam at the top) and the economic chaos of the 1970's resulted in both parties moving right. This sets the stage for the remaining two chapters. Chapter 8 is on the two Bush presidents (plus GHWB's father Prescott) and why they were centrists in their own way. Chapter 10 is on the three Democrat presidents, Carter, Clinton and Obama. According to Brown all were centrists, although they were consistently accused of being liberal, perhaps socialist. Carter inherited a terrible economy of stagflation and didn't improve things--leading to Reagan's election. Bush 41 carried on from Reagan and pragmatically defeated Iraq and was there during the collapse of the Soviet Union--the handling seemed pragmatic, but can be criticized for several reasons. Clinton was quite conservative by Democrat standards (a "New Democrat") and is known for tax increases and cutting welfare; his early attempts at universal heath insurance and social issues did not go well. Bush 43 inherited a federal surplus and squandered it away in tax cuts, a Medicare drug plan that favored pharmaceutical companies and a couple of wars after 9/11. Perhaps he gets a pass for the 2008 subprime debacle because he had not a clue what was happening (in which case, Bernanke, Paulson and Geithner take the blame. Obama gets little coverage; perhaps adding him was an afterthought.
The overall impression is analysis gets complicated. Each group has their time to be effective (the New Deal for liberals, Eisenhower for centrists, and Reagan for conservatives). Disasters (and near-disasters) also occur: the 1920's under conservatives or 1950's if Taft was president; the 1930's if Hoover was reelected; the 1960's under LBJ (and Nixon) when liberal programs went too far; or 1970's moderates who failed to make needed changes.