IT HAS BEEN WIDELY reported since Super Tuesday that John McCain has effectively sewn up the Republican nomination for president but must still convince enough American conservatives that he stands as heir to Ronald Reagan. This poses an obstacle to his election in November. McCain might be more successful in wooing conservatives if he claimed the mantle of a different Republican icon, Winston Churchill, a maverick distrusted in his day by Conservatives and a man whom McCain praised frequently in his books. The parallels between McCain and Churchill are striking and instructive.

Both grew up as underachievers in the shadow of prominent fathers and ancestors and then surpassed them in renown. Churchill's father was chancellor of the Exchequer, a descendant of the Duke of Marlborough who defeated the armies of Louis XIV, while McCain's father and grandfather were prominent admirals. Both McCain and Churchill were fearless soldiers and prisoners of war, although Churchill escaped Boer captivity after mere weeks while McCain endured more than five grueling years at the Hanoi Hilton. Both have felt most at home in battle, whether in war or political chambers, and have shared a restlessness to advance their own careers and the cause of their countries.

Neither Churchill nor McCain was ever liked much by his colleagues. Perhaps early on Churchill was more liked and his brilliance more respected, but he switched from the Conservatives in 1904 to the Liberals with much newfound partisan fervor, and the Conservatives never forgave him even after he returned to the fold in 1924--even after he won WWII. Churchill's dispute with the party leadership over control of India (he favored it), Nazi Germany (he was against it), Zionism (he was for it), and other divisive issues, as well as his occasional outreach to Labourites--indeed, he headed a wartime coalition government--did not help his popularity among the party faithful. McCain has always been a Republican, but, without being the partisan warrior Churchill was, he has never been personally popular with his party colleagues. He further alienated the party faithful and establishment by co-sponsoring legislation with Democrats. Both have been perceived by colleagues as erratic, and occasionally harsh in personal relations.

Fundamental to Churchill's worldview was the belief that priorities had to be rigidly ranked and that the supreme interests need to be vigorously and single-mindedly pursued. Chief among those interests was national security. McCain has suggested a similar approach. Indeed, McCain and Churchill lived and breathed national security issues, and it is in this policy field that their similarities are most pronounced. They both strongly believed in their countries, considering them the chief champions of civilization, and they have been rarities in usually putting national security interests ahead of their political fortunes.

From the time he became First Lord of the Admiralty shortly before WWI, Churchill was mostly tough-minded and prescient about major national security issues. He took the unpopular stands of seeking to overthrow the new Bolshevik government in 1919-1920 (derisively dubbed "Churchill's War"), warning against the rise of the Nazis in the 1930s when appeasement was overwhelmingly popular, and then privately and publicly warning against the emerging Soviet threat shortly after Yalta in early 1945 when the British people were exhausted after almost six years of war.

Churchill dismissed the political consequences of his positions on preeminent matters. Indicative of his attitude was his private response in 1919 to criticism over his anti-Bolshevik crusade: "I cannot help feeling a most dreadful & ever present sense of responsibility. Am I wrong? How easy for me to shrug my shoulders & say it is on the Cabinet, or on the Paris [Versailles] Conference. I cannot do it." Although steadfast in principle, Churchill remained tactically flexible, making alliances even with despised regimes and former enemies in order to advance British national security interests against those he usually depicted as foes of Western civilization.

McCain has also often taken gutsy and discerning stands on national security. He stood up and supported the Kosovo war despite personal misgivings and general Republican apathy over what they deemed "Clinton's war" because he thought it necessary to rally around the president and troops in time of battle. McCain also gave the most persuasive argument why containing Saddam Hussein was untenable, and then after 2003 became a persistent critic of the management of the war, including troop levels, before taking the unpopular (even among Republicans) early stand of supporting the surge, which has made significant advances. He often sees conflicts within a clash of civilizations, warning about the threat posed by radical Islam, while remaining flexible in tactics and alliances. McCain has also persistently warned against the danger of a nuclear Iran, and even raised the idea of bombing Iran's nuclear sites when much of the country is wary of new military engagements. A McCain administration would make our enemies nervous in ways that no president has since Bush in 2001-03 or Reagan for much of his tenure.

It was Churchill's credibility, earned by staking out unpopular but prophetic positions, that led him to be embraced by his political nemesis Prime Minister Neville Chamberlain when war broke out in 1939, and then catapulted him to replace Chamberlain over war mismanagement in 1940. After shockingly losing the postwar election in 1945, Churchill regained the premiership in 1951 by seizing on the Labour government's failures in economic and foreign affairs. He coopted the political center by advocating, in place of bitter party strife, a "solid stable administration by a government not seeking to rub party dogma into everybody else."

It was McCain's unique national security credibility that similarly brought him back into the good graces of his more powerful political rival, President George W. Bush, and he can legitimately offer himself as a competent and effective wartime commander in chief. But McCain now can attain the presidency only if he also reaches out to the political center, or independents, as he has before.

Adhering to party orthodoxy is no guarantee of greatness. Churchill often diverged from the party line, but he emerged undeniably the greatest leader of his party, country, and the West of his era. Indeed, Stanley Baldwin, prime minister of the mid-1930s, was a most popular Conservative party leader but is remembered by history for dawdling while Nazi Germany rearmed. Churchill memorably claimed publicly in 1936 that the Baldwin government was "resolved to be irresolute, adamant for drift, solid for fluidity, all-powerful to be impotent," and later lamented privately he would have preferred Baldwin never had lived. Churchill was far more gracious toward Chamberlain, who at least tried to do something to blunt the Nazi threat, however disastrous the result of his appeasement policy.

McCain certainly has not achieved Churchill's heights, but he can legitimately claim to be the most Churchillian among the Republicans of his day. That not only offers hope for a possible McCain administration, especially during this time of war, but should also be encouraging to conservatives.

Michael Makovsky, foreign policy director of the Bipartisan Policy Center, is a former special assistant in the Office of Secretary of Defense, 2002-2006, and is author of the new book Churchill's Promised Land (Yale University Press).