Airline Partners Australia (APA) has stepped up its battle for Australian national flag carrier Qantas.
APA has been working hard to push the deal through
The consortium has taken out full-page adverts in several national newspapers urging investors to accept its 11.1bn Australian dollar bid ($9.2bn; £4.6bn).
Latest figures show just 27.8% of Qantas shareholders have accepted the offer, well short of the 70% needed.
Investors remain sceptical about the bid, despite APA offering incentives to push the deal through, analysts said.
Adverts in several national newspapers on Tuesday warned Qantas' share price was likely to fall if the bid was not accepted, saying: "Accept now the best Qantas share price ever."
"APA is aware that an overwhelming majority of small and large Qantas shareholders support the offer," said APA director Bob Mansfield said. "Now is the time for those supportive shareholders to accept. If the bid fails, the share price will almost certainly fall."
APA has offered A$5.45 a share for the airline - its shares closed at A$5.36 on the Australian market on Tuesday.
It also underlined the fact that the Qantas board has unanimously backed the bid as "fair and reasonable".
The consortium - which includes Australia's Macquarie Bank and Texas Pacific Group - has been working hard to drive the deal through. Its offer closes on 4 May.
On Sunday, APA offered to speed up payments for stakeholders who accepted the offer within five days of the bid closing - paying out in five days rather than 30.
Last month it eased its offer conditions after some key shareholders opposed the deal. It now needs just 70% backing rather than the previous 90%.
However, one institutional investor - Balanced Equity Management - is standing fast and refusing to sell, as it believes the offer undervalues the company.
However, APA's adverts were not the only reason Qantas hit the headlines.
According to a report in the Australian Financial Review the flag-carrier has decided to buy a 30% stake in Vietnam's Pacific Airlines.
The move would be consistent with the group's strategy to expand in the Asian market in an effort to take on low-cost rivals such as Tiger Airways and Air Asia.