Although recognised as an "institution" of Thai politics, critics point to its conservative and bureaucratic working style as one of the reasons why the party has failed to lead at the polls.
In April this year, right after the Democrats celebrated their 67th anniversary, former deputy leader Alongkorn Ponlaboot urged his party to reform or risk being irrelevant not just to voters but the public at large.
"Some people in the party may think we have lost in elections because we didn't have as much money as our rivals," Mr Alongkorn said.
"There are people, myself included, who believe that we lost because we did not have enough vision and have failed to catch up with people's changing needs and expectations."
Democrat leader Abhisit Vejjajiva acknowledged the need for his party to undergo reform. He earlier said the main platform for the Democrats' "Operation Change" would be in opening up the party so people outside can have a say in how it will reshape itself as it moves forward.
The party's expanded executive board _ comprising 35 people instead of 19 as in the past _ is the most visible change the party has made.
That the new board is comprised wholly of old faces _ all of them are the party's veteran politicians with ties to the existing leadership _ raises the question of whether it will be able to usher in change.
The new executives include such familiar names as Sirichoke Sopha, Chamni Sakdiset, Thepthai Senpong and Khunying Kalaya Sophonpanich.
Kiat Sitheeamorn, one of the party's reform committee members, and a deputy leader, asked members for their input.
"The comments came in and they were largely focused on the party not being open, and slow to move," Mr Kiat said.
"We used to have a 19-member executive board. Deputy party leaders were elected by the assembly. They were charismatic and capable but were not necessarily selected by the party leader.
"Rather, they were people whom party branches and MPs had chosen," he said in an interview with the Bangkok Post.
The question was how much, if at all, the deputies were able to work with the party leader who did not pick them. Quite often, the working efficiency between them was damaged.
"That prompted a change whereby the party leader must have his own team who answers to him. That would increase efficiency and forge teamwork spirit," Mr Kiat said.
As for the deputy leaders in the regions who were not suited to the task, this problem has been addressed, he said.
For example, the deputy for the Northeast was working well in some provinces, although he must ensure political activities are conducted consistently, not only during elections.
To address this, the party set up a system of provincial clusters of party executives with the heads being equivalent to deputy party leaders. The cluster heads are not necessarily elected at the party assembly.
"The party leaders and secretary-general will work proactively and fully in different constituencies," Mr Kiat said.
"They reserve the right to name the provincial cluster heads who are supposed to be suitable, capable and well connected.
"The heads will supervise the party branches, nominate the MP candidates, and oversee activities before and after the elections.
"They must also determine how many MP candidates should stand in the region and how many of them have a chance to win. Previously, these were the responsibilities of the regional deputy leaders.
"But they could not adequately supervise the [vast] regions."
Asked whether the party can meet budget requests or demands from branches, Mr Kiat said: "I've made an assessment before and found some branches were doing well and others were not, depending on whether the party had MPs in the respective localities.
"If we had a standing MP, the branches were strong. This is where we must improve. Under the new structure, the permanent staff in charge of developing each branch will work alongside the provincial cluster, which is something unprecedented. Once the Election Commission endorses the party's executive board appointment, the provincial cluster heads can be selected right away."