The phrase "a major factor and" is correct and usable in written English.
It can be used when discussing the importance of a particular element in a broader context, often leading into additional points or factors.
Example: "In the success of the project, a major factor and the team's dedication played a crucial role."
Alternatives: "a significant element and" or "a key contributor and".
Racism was a major factor, and so was public and private indifference.
The performance of Wall Street was a major factor, and proved as erratic as London.
"If efficiency becomes a major factor — and it will — this could be one way our design language evolves".
The most optimistic interpretation is that new immigrants are a major factor and that as they assimilate, they will move up and into the middle class.
"The timeliness of the information is a major factor, and the volume of message traffic can be very dangerous," said Keith Eiler, a military historian with the Hoover Institution at Stanford University.
Many economists and health policy specialists think that changes made by insurers, hospitals and doctors to emphasize the quality of care rather than the quantity of care is a major factor, and Children's Hospital Boston offers a good test case.
Lastly, for the case of the social network-based graph we evaluate different vaccination policies; the criteria are based both on individual characteristics -age being a major factor- and on the contact patterns.
I do think that the 20% of Americans who voted for Ross Perot, or their avatars, will be a major factor next year, and both sides would ignore them at their peril.
It is the most variable characteristic of the atmosphere and constitutes a major factor in climate and weather.
Nitrogen is a major factor for eutrophication and biodiversity loss and contributes to global warming.
Hydrogenic landscapes constitute a distinguishing mark of the Polesie and are a major factor attracting tourists and artists.
