美國總統選舉的兩輪制，兩輪選舉都是以普選方式進行，首輪為總統候選人提名，第二輪為大選。兩輪選舉都是以普選方式進行。根據法例，在選民登記冊上登記政黨聯繫為民主黨的就是民主黨人。
兩輪選舉由美國的50個州各自立法規範，由於美國總統基本上是民主與共和兩黨之爭，這裏只討論兩黨的提名制，並集中討論加州的民主黨初選。
全國性規範
民主黨對各州的提名要求有一定限制，其目的是令限制不太苛刻。它要求對有意參加初選的總統候選人的州內提名不超出5000名民主黨人和提名費不超出2500美元。民主黨黨員被鼓勵參選黨代表，若該州要求有意參選黨代表的黨員提交簽名，其簽名人數不應超出該區的0.5%的民主黨選民人數，或該區的上屆初選的總票數，或500人，以少數為準。
各州規定
在2020年2月加州選民登記冊上的民主黨聯繫的有936萬(45%)，共和黨493萬(24%)，無黨派513萬(25%)。2016年的加州民主黨初選的總投票為517萬。
加州採用半開放制，只有在選民登記冊上的政黨聯繫登記為民主黨或無派別的才能參加民主黨初選。因而加州的個國會區的0.5%民主黨員平均數約為800人。
讓我們看看阿拉巴馬州的初選選票。總統候選人應該在各國會區提交的黨代表名單，讓選民在初選中投不多於5名黨代表。黨代表需要為該國會區選民。
總統候選人若在某一國會區中取得超過15%的選票，他/她就會按比例分得國會區黨代表權。實際的國會區代表名單將在隨後的黨團大會上決定，因為民主黨要求出席5月13至16日民主黨全國大會的代表男女人數均等及各民族按一定比例出席，因此，其揀選人選有特別安排。
超過15%得票的總統候選人若得到代表人數超出於國會區數目的3倍，他/她將在每區獲得3名代表，分配按男女平衡及民族比例揀出。餘下的黨代表權會在再稍後的黨團會議中以州黨代表和黨領導代表交配，被分配的必需在代表那名總統候選人。
全國代表大會
若民主黨的總統候選人不能在6月中的全國代表大會前取得絕數多數的承諾代表(即透過首輪選舉產生的黨代表)，則需要在全國代表大會中進行實質投票。這時，因其他候選人在中場棄選而遺留下來的黨代表則有可能按個人意願投票(按州立法而定)。假若這一輸投票還不能過半數(1991代表人票)，由州長、眾議員、參議員等組成的771個超級代表就可以按個人意願在第二輪投票中投票。不過，這只是理論問題，因為若主要政黨不能在初選中出現強勢候選人，它往往在總統大選中落敗。
獨立候選人
以阿拉巴馬州為例，獨立候選需要取得3%的最近一屆州長選舉總票數的公民提名才可以被提名參與11月的總統大選。
小數黨派
在上屆選中取不到該州的2成選票的就在法律上定為小數黨派。它的候選人需要取得3%的最近一屆州長選舉總票數的公民提名才可以被提名參與11月的總統大選。
討論
親中人士時常以美國總統選舉並非直接以一人一票選出，而質疑美國不民主和為香港的不民主制度護短。臭名遠播的有回歸前明報老闆查良鏞在明報社論發表的以美國選舉為例，解說香港普選不需要一人一票。
民主的原則是其選舉制度能夠基本上反映大多數公民的意願。中共在基本法上寫下的選舉制度，從設計上已是令中共可以操控特首選舉和立法會選舉，因而不能與美國選舉相題並論。
以美國總統民主黨初選的加州為例，加州國會區黨代表約相當於其初選中的1萬2千票。因此，代表人制可理解為某種的四捨五入制。這種設定從原意沒有偏幫兩大政黨，因此並沒有操控成份。
在龐大的選民基礎下，當兩名候選人的票數接近時，選民的意願就可以看作均等，只要依選舉法作出勝負決定，四捨五入制並無不妥。
所有選舉制度都有其歷史因素，美國的總統制和英國的首相制都符合民主原則。在討論此兩制的比較時，應該著點在美國的與英國的政黨制度，英國以黨主席任首相，這令英國的最高決策人受到其政黨制衡；但美國的民主制度也有大量制衡機制，當中包括但不限於眾議院、參議院和三權分立。英國的執政和在野政黨的基層黨團可能較美國活潑和更有機會起到間接的監察作用。
由此推論，嚴格的一人一票制不是民主制度的核心。反而，該制度促成的基層黨團的角色更為重要。
參考
1
Democratic National Convention
California Democrats will send 494 delegates and 35 alternates to the Democratic National Convention in Milwaukee, Wisconsin. All pledged delegates are allocated to the presidential candidates according to the results of the March 3, 2020 Primary. At-Large and PLEO Delegates are chosen by the Presidential Campaigns, keeping in mind our affirmative action goals, and confirmed by the Statewide Delegation at the May 17th meeting.
2020 Delegate Selection Plan (Adopted at Executive Board meeting 8/25/2019)
California is divided into 53 Congressional districts. Each district elects a representative to serve in the United States House of Representatives as part of the California's congressional delegation.
Current districts and representatives
The delegation has a total of 53 members, with 46 Democrats (including Speaker of the House Nancy Pelosi) and 7 Republicans (including minority leader Kevin McCarthy).
The 416 pledged delegates California sends to the national convention will be joined by 79 un-pledged PLEO delegates (30 members of the Democratic National Committee; 48 members of Congress, including two Senators, notably Kamala Harris, as well as 46 U.S. Representatives, notably Eric Swalwell; and the governor).
2
California Code, Elections Code - ELEC § 6524
The name of any presidential candidate, to whom are pledged a group of candidates who have qualified by petition for the delegate selection portion of the presidential primary ballot, shall, in addition, be automatically placed on the presidential preference portion of the ballot, without the filing of a separate petition for the presidential preference portion of the ballot.
California Code, Elections Code - ELEC § 6061
Any uncommitted delegation desiring to be placed on the presidential primary ballot shall have nomination papers circulated on behalf of the candidacy. In order to qualify for placement on the presidential primary ballot, the candidate's or uncommitted delegation's nomination papers shall be signed by voters registered as affiliated with the Democratic Party equal in number to not less than 1 percent or 500, whichever is fewer, in each congressional district of the number of persons registered as members of the Democratic Party in the report of registration issued by the Secretary of State on the 135th day preceding the presidential primary election. (4.5 months)
C. If a state requires the filing of a petition with the signatures of registered/enrolled voters in order to have a delegate/alternate candidate gain access to the primary ballot in connection with the Democratic presidential nominating process, the number of valid signatures shall not exceed either one half of one percent (.5%) of the registered/enrolled Democrats in such district or one half of one percent (.5%) of the total votes in such district for all Democratic presidential candidates (including uncommitted) during the immediately preceding presidential nominating process, whichever is lower, but in no event shall the number of valid signatures required exceed 500.
2. District-level delegates and alternates shall be elected by a presidential preference primary followed by a post-primary caucus, with the first determining step on March 3, 2020.
a. A presidential preference primary will be held on Tuesday, March 3, 2020, followed by District-level delegates and alternates caucuses on Sunday, April 19, 2020 to elect delegates.
a. California ’s district-level delegates and alternates are apportioned among the districts based on a formula giving equal weight to total population and to the average vote for the Democratic Candidates in the 2012 and 2016 presidential elections.
3
Rule 15 Petition Requirements and Filing Deadlines
A. If a state requires the filing of petitions with the signatures of registered/enrolled voters as the sole method to place a presidential candidate’s name on the primary ballot in connection with the Democratic presidential nominating process, such number of valid signatures shall not exceed 5,000.
B. No fee in excess of $2,500 may be charged (either to a presidential campaign or State Party) as the sole method to place a presidential candidate on the ballot in connection with the Democratic presidential nominating process. If state law requires such a fee in excess of $2,500, such law was in place prior to 2018, and a State Party has taken provable, positive steps to change such law, then a State Party may seek a waiver of this provision to charge such a fee to presidential campaigns.
C. If a state requires the filing of a petition with the signatures of registered/enrolled voters in order to have a delegate/alternate candidate gain access to the primary ballot in connection with the Democratic presidential nominating process, the number of valid signatures shall not exceed either one half of one percent (.5%) of the registered/enrolled Democrats in such district or one half of one percent (.5%) of the total votes in such district for all Democratic presidential candidates (including uncommitted) during the immediately preceding presidential nominating process, whichever is lower, but in no event shall the number of valid signatures required exceed 500.
4
California has semi-closed primaries — Californians must register as democrat or undeclared to vote for Bernie!
陶君行憶述當年的情況：「號稱公信力第一的《明報》社論，竟然發表全世界沒有一個地方是一人一票選舉產生的謬論。」《明報》社長查良鏞的言論令我們非常憤怒，他以美國總統的候選人制和英國的議會制為例子，引證香港也不需要一人一票的選舉制度。而身為政制小組港方召集人的查氏有了身份衝突，於是我和香港理工大學及香港樹仁大學的同學決意揭露其醜惡，跑到明報總部火燒《明報》，高喊『你有你強詞奪理的自由，我有我火燒《明報》的道理』」[19]可惜，行動至此沒有後續，亦未能喚起廣大市民認識這個小眾共識而來的普選程序。
March 3, 2020, Presidential Primary Election Republican Delegate List
How are presidential primary elections conducted in California?
Qualified political parties in California may hold presidential primaries in one of two ways:
Closed presidential primary - the party only allows voters indicating a preference for that party to vote for its presidential nominee.
Modified-closed presidential primary - in addition to allowing voters indicating a preference for that party to vote for its presidential nominee, the party also allows voters who did not indicate a party preference to vote for its presidential nominee.
If a qualified political party chooses to hold a modified-closed presidential primary, the party must notify the California Secretary of State no later than the 135th day before Election Day.