Oracle on Tuesday threatened to withdraw its bid to purchase BEA Systems if BEA doesn’t let its shareholders vote on the proposal by Sunday.

BEA yesterday rejected – for a second time – Oracle’s proposal to purchase the company for $17 per share, or $6.7 billion, according to a letter sent by Oracle President Charles Phillips to BEA’s board of directors Tuesday morning. BEA contends the offer significantly undervalues the company, though Oracle says it represents a 21% premium over BEA’s share price on Oct. 8, the day before Oracle made its takeover bid.

“The [BEA] board has refused to meet with us since we made our October 9th proposal,” Phillips wrote in the Tuesday letter. “Oracle has no interest in a long, drawn-out process to acquire BEA. If the BEA board refuses to execute an acquisition agreement and refuses to let their shareholders vote, then our $17 per share proposal to acquire BEA will expire at 5 p.m., PDT, on Sunday, October 28, 2007.”

Oracle’s threat to take its proposal off the table caused BEA’s shares to drop in price, according to The Wall Street Journal. BEA shares rose initially after Oracle announced its takeover bid, reaching $18.59 on Nasdaq Monday. The price has since fallen to $17.85, the Wall Street Journal said.

BEA’s first rejection of Oracle’s offer came in a letter dated Oct. 11. “It is apparent to our board . . . that BEA is worth substantially more to Oracle, to others and, importantly, to our shareholders than the price indicated in your letter,” BEA wrote. “We are very sensitive to the fact that Oracle is a direct competitor of BEA. Therefore the Board cannot consider any process which is long in duration, open-ended in nature, or would divulge competitively sensitive information which could materially harm our business and our shareholders’ interests.”