Delineating a national agenda and requiring each candidate to follow is not the best way for the Democrats to take control of the U.S. Congress in 2018. After a political party loses the White House, voices call for the party to effectuate a message that each member running for election or re-election is requested to repeat to his/her voters. The Democratic Party is currently in that mode. U.S. House Democratic Caucus Chairman Joe Crowley of New York recently told the Associated Press: “The message is being worked on. We’re doing everything we can to simplify it, but at the same time provide the meat behind it as well.”

However, in a system with just two dominant political parties, it is sagacious for the party high command to instruct each candidate to establish a message that puts them in the mainstream of their respective electorates.

Ideological purists who derisively brand any independent-minded party member as a RINO (Republican in name only) or DINO (Democrat in name only), work assiduously to get the most ideologically unadulterated Congressional nominees to run even in parts of the country where only a moderate can win. Sometimes, the ideological candidate upsets the apple cart and wins the nomination. However, it is often the case that the candidate will suffer an ignominious defeat in the General Election.

We see this phenomenon at the Presidential level. In 1964, conservatives disaffected by the influence of the moderates and liberals, rebelled against more moderate candidates and supported rock-rib conservative Barry Goldwater. In the General Election, Goldwater made few overtures to win-over moderate voters, instead declaring: “Let me remind you that extremism in the Defense of liberty is no vice. And let me remind you also that moderation in the pursuit of justice is no virtue.” Goldwater lost in an electoral landslide. He won only one state outside of the Deep South, his home state of Arizona. Four years later, the party nominated the moderate former Vice President Richard M. Nixon and won the White House.

Contrariwise, in 1972, the “new left” rallied behind the candidacy of liberal U.S. Senator George McGovern. McGovern, once a 200-1 long shot, defeated more moderate candidates and garnered the Democratic nomination. Like Goldwater, McGovern made no attempts to moderate his message. Consequently, he won only the District of Columbia and Massachusetts. Four years later, the party begrudgingly nominated the moderate former Georgia Governor Jimmy Carter and won.

The 2010 Congressional elections taught the GOP the folly that comes with ideological purity. The Republicans were whisker-close from taking control of the Senate. However, ideological purists came out in the primaries and nominated candidates who were too conservative for their constituencies. In Delaware, Mike Castle, a moderate-liberal Republican, was the favorite to win the GOP Senate nomination. Castle, a former Governor, was the state’s at-large representative since 1993. He was one of few Republicans who could have won the General Election. Castle was popular in the left-leaning state.

However, conservatives, believing Castle a RINO, supported conservative Christine O’Donnell who subsequently lost the General Election by 17 percentage points.

In addition, that year the GOP nominated two other Senate candidates who were too conservative for their states. In Colorado and Missouri, both candidates ceded the center to their Democratic opponents and lost the election.

From 1931-1995 (for all but four years), the Democrats held a majority in the House. During their days of electoral hegemony, the Democratic Party was greatly divided, with a liberal, moderate, and conservative bloodline. When Franklin D. Roosevelt and Lyndon B. Johnson were in power, the Democrats maintained control of the Congress with the help of conservative Southern Democrats. While they proved a nuisance for both liberal Presidents, without these members the congressional majority might not have been maintained.

The Democratic Party held the House for such a long period of time, not by following a message telegraphed from the party’s high command, but by letting individual candidates craft their own messages. In 1938, Roosevelt tried to purge conservative Democrats in primaries by supporting liberal opponents and failed miserably. Only one of Roosevelt’s supported challengers ousted an incumbent. Democrat. The conservative Democrats were a good fit for their constituencies.

In 2006, under the tutelage of the Chairman of the Democratic Congressional Campaign Committee, Rahm Emanuel (D-IL), the party won the House for the first time in 12 years, picking up 31 seats, the most seats since 1974. They did this by recruiting candidates who would be palatable to the electorate in their districts, not necessarily palatable to the national party. Twenty-two incumbent Republicans lost.

The Democratic recruits had the liberty to elucidate their own messages. That year, former NFL Quarterback Heath Shuler ousted incumbent Republican Charles Taylor in North Carolina not by advertising himself as a tribune of “Democratic Values” but of “mountain values.” Shuler’s opposition to abortion rights and additional gun control measures inoculated him from being tethered to the more liberal national party. On other issues, like opposition to the Central American Free Trade Agreement, which Shuler like most Democrats opposed, he sang from his party’s song sheet.

Emanuel’s counterpart at the Democratic Senatorial Campaign Committee, Chuck Schumer of New York, superintended a similar strategy. He recruited Democrat Bob Casey Jr. in his bid to oust incumbent Republican U.S. Senator Rick Santorum. Casey’s support of gun rights and his opposition to abortion rights were in sync with rural central Pennsylvania voters. Since both candidates were social conservatives, social issues were neutralized, and Casey was able to focus on economic and foreign policy issues where the Democrats harbored an advantage.

Rather than establishing broad themes and letting the candidates decide what to run on, Democratic National Committee Chairman Thomas Perez appears to be setting up an ideological litmus test. He recently stated: “Every Democrat, like every American, should support a woman’s right to make her own choices about her body and her health. That is not negotiable and should not change city by city or state by state.”

But for the Democrats to capture a Congressional majority, they must nominate candidates ideologically in line with their respective electorates. In some cases, that means nominating anti-abortion, conservative Democrats in districts where the national Democratic Party is to the left of the electorate.

For example, since 1991, U.S. Representative Colin Peterson represented a rural district in Minnesota. Peterson is one of the most conservative Democrats in Congress. However, his conservatism has allowed the Democrats to keep the district in Democratic hands despite giving Republican Presidential nominee Donald Trump 6.1.8% of the vote in 2016. The only way the Democratic Party can keep this conservative district is by supporting a conservative candidate. Nominating a liberal here would constitute political suicide.

In a system with just two major parties, a party can only capture a Congressional majority by giving candidates the leeway to define their own messages and position on issues. Being called a RINO or a DINO might actually be a badge of honor for candidates running in the opposing party’s electoral terrain. Democratic candidates should not be pressured by party leadership to take positions supported by party chieftains. They should be given the latitude to define their own message. This would be politically wise.