Mexico's presidential candidate Andres Manuel Lopez Obrador of the Morena party waves after presenting his registration at the Mexican Electoral Institute in Mexico City, on March 16. | Carlos Tischler / Sipa via AP Images

LOS ANGELES—The campaign season has officially begun in Mexico, leading up to the presidential elections on July 1.

In California, supporters for the left candidate Andrés Manuel López Obrador (AMLO) held a caravan that began in Northern California and ended on Easter Sunday in Los Angeles, where the largest population of Mexican nationals living in the United States lives. They made stops in key cities, spoke about their candidate and assisted Mexican nationals in registering to vote.

The caravan was organized by committees of the National Regeneration Movement Abroad (Morena en el exterior), a movement to bring about change for the people of Mexico. The committees consist of Mexicans living outside of Mexico who have come together to elect a president who they believe can better the conditions of their families back home—conditions, in many cases, that forced them to leave and come to the U.S.

Morena (Movimiento Regeneración Nacional) begin as a movement demanding an end to poverty, corruption and privatization of natural resources within Mexico. In 2014 it became a registered political party and received a record number of votes for a new party in the 2015 elections for the Chamber of Deputies.

Prior to the opening of the presidential election campaign, Morena en el Exterior committees had been busy spreading the word of their movement and showing how Mexicans living abroad could play a role.

Mexicans abroad with a voting credential could vote for president before 2012, but had to go to Mexico to vote. After 2012 any Mexican citizen with a voting credential can request their ballot sent to their residence outside of Mexico. This may sound easy enough. But according to Marta Alvarado of Comité Morena Fuerza y Unidad (Morena Committee for Power and Unity), Mexicans whose voting credential has expired or has been lost need to make an appointment at their nearest consulate.

“Many times the consulate don’t answer the phone,” said Ms. Alvarado. “We call and call but no one answers, and when they do answer the caller is told there are no more appointments.” Alvarado organized a group to meet with the consul general in Los Angeles to resolve this issue. Special appointment times were set aside.

The next step after obtaining your voter card is to register to vote online. Many times the system was down, frustrating many would-be voters. Morena committees encouraged people not to give up and offered assistance with access to computers and the Internet. After registering, you had to provide proof of residency that you actually lived at the address you noted outside of Mexico, and the mailing date on that proof had to be within three months. This meant you had to go back into the system and provide that information, which again was frustrating and cumbersome. Morena members sometimes worked long hours attempting to catch the system when it was up in order to assist fellow Mexican citizens.

The caravan stretched 23 cars long as they passed through the predominantly Mexican communities of Los Angeles. Other committee boosters waved Morena flags as the caravan passed. “It was emotional and uplifting to see the support we received as we passed through the streets,” said Ms. Alvarado.

The committees will continue to grow their movement by assisting Mexican nationals who already have their voting credentials to register to vote. They have until April 30.

“I know that our candidate Andrés Manuel López Obrador will win,” said María as she was joining Morena. “He is up by 18 percentage points in the polls, but we will have to be ready to defend our vote as there has been wide voter fraud in past elections.”