Colorado voters may want to think carefully before voting for ranked-choice voting, a ballot issue in the general election this November. It will mean the end of the two-party system as we have known and practiced it in Colorado for almost 150 years.

Ranked-choice voting will do away with the Democratic Party primary elections and the Republican Party primary elections. It will replace those elections with a complicated system which uses second-choice votes, third-choice votes and fourth-choice votes to determine who gets elected to political offices in Colorado.

If you look closely at the ballot language, you will find a long list of state officials who will no longer be elected under the two-party system.

The “governor and lieutenant governor, the secretary of state, the state treasurer, the attorney general, members of the state board of education, and regents of the University of Colorado” will be under ranked choice.

So will “U.S. senator, representative to the U.S. House of Representatives, … and state senator or state representative serving in the General Assembly.”

Got all that? Ranked-choice is going to apply to all the state officers (governor, etc.), the state Board of Education, the University of Colorado Regents, our U.S. senators and representatives in Washington, D.C., and all the members of the state legislature in the state Capitol in Denver.

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Ranked-choice voting is not a little experiment affecting a small part of Colorado state government. It is a complete overhaul of the election of state officials and Colorado’s senators and representatives in the U.S. Congress as well.

The two-party system has served the United States well since the first decade of its existence. Thomas Jefferson founded the first political party, the Democratic Republicans, to aid in his election as president in 1800. The Federalist Party was organized in opposition to Jefferson.

By the mid-19th century, it was the Democrats versus the Whigs. Then the Republican Party was created to abolish human slavery, which was accomplished by the American Civil War in the early 1860s.

By the early 20th century, the two-party system evolved into what we know today — the Democrats versus the Republicans.

That is a long successful history for the two-party system. It is risky to replace it with a complex alternative which has only been tested in two other states (Maine and Alaska) with small populations and in a limited number of cities across the country.

Political parties play an important role in recruiting and training new candidates for state government offices and the state legislature. Would-be elected officials often start by working their way up in the political party, making connections and building support as they go.

We doubt that way of building a career in politics will be available if the political parties are reduced in power under ranked-choice voting. Candidates will have to gain support and get elected on their own.

Polls reveal many voters who register unaffiliated actually have an underlying preference for one of the two major political parties over the other. The result is that, for most voters, the cue of which political party a candidate belongs to is the strongest guide to how voters cast their vote.

Political parties thus bring voters together for common action. Political parties organize our electoral lives and enable us to join with others in the effort to achieve shared policy goals.

It is also worrisome that downgrading political parties will further increase the role of money in who wins elections in Colorado. With party membership reduced as a factor in voting, money raised to buy political advertising will become even more important in Colorado elections than at the present time.

You may have heard that, if ranked-choice voting is approved by the voters, it might not go into effect immediately. A clause added to a bill recently passed by the state legislature forbids ranked-choice voting at the state level until it has been tried in 12 Colorado municipalities in counties of a certain size and with a specific demographic makeup.

That new state law, passed this year by the state legislature in anticipation of ranked-choice voting, may be unconstitutional.

However, we think it is important to oppose ranked-choice voting when it is on the ballot this November. If ranked-choice voting is approved by voters statewide, there will be a great deal of pressure to brush that limiting law aside and put ranked-choice voting into effect in Colorado immediately.

Briefly, here is how ranked-choice voting works: There is an “all candidate primary election” in which everyone who wants to win the particular political office runs for it. There is one vote for each voter. The four candidates receiving the highest number of votes advance to the general election.

In the general election, voters will rank the four candidates 1, 2, 3 and 4. If no candidate gets a majority of the vote on the first round, the fourth-place candidate is removed and their second-, third- and fourth-place votes are distributed to the other candidates. This process goes on until one candidate has a majority of the votes and wins the election.

One of the major problems with ranked-choice voting is its stupefying complexity, particularly in the general election. Many voters will have trouble comprehending how their vote is connected to who gets elected and is serving in office.

We think the keywords in elections are visibility and responsibility. Voters should be able to see clearly the one candidate they are casting their one vote for. At the same time, elected officials should be directly responsible to voters who have voted directly for them.

The big drawback with ranked-choice voting is it obscures and muddles up the relationship between the voters and their elected officials. Vote “no” on ranked-choice voting in Colorado.

Bob Loevy is a retired professor of political science at Colorado College who writes about Colorado and national politics.