The six Democrats - Jan Schakowsky (Illonois), Michael Michaud (Maine), Rosa DeLauro (Conneticut), George Miller (California), Barbara Lee (California) and Peter Welch (Vermont) - said the current proposals would have "profound and long-lasting consequences".
In the letter, sent yesterday, the Members urged Obama not to make any final trade agreements "that affect critical health issues" until members of the public and Congress have had the opportunity to review the provisions and provide input.
In particular, they argued that proposed provisions relating to data exclusivity, patent registration and procedure and enforcement would "delay generic competition and increase the price of medicine" and lead to "preventable illnesses and deaths".
"Certainly, trade negotiations conducted behind closed doors are not the place to make changes that would have such profound consequences for patents and veterans, as well as state and federal budgets," they wrote.
Although the TPP negotiations were meant to have been conducted in secret, whistleblowing website WikiLeaks has released several documents which suggest the US is exerting "great pressure" on other nations to adopt stricter IP policies. In the latest release, yesterday, WikiLeaks published two leaked documents that suggest that the US is isolated in its positions on many IP policies.