While the EC waits for a reply, it will still organise the polls as planned, despite concerns surrounding the election, said EC secretary-general Phuchong Nutrawong.
If the caretaker government agrees with the proposal, the EC will "cancel all the work it has done so far", Mr Phuchong said.
The EC's letter cited six reasons why the caretaker government must request a royal decree to delay the Feb 2 election, which has been met with widespread protests.
One reason is that election candidates in 28 constituencies of eight southern provinces were stopped from registering by supporters of the anti-government People's Democratic Reform Committee (PDRC).
Another reason is that in 16 constituencies there is only one candidate eligible to vote for.
The EC's letter also cited concerns of the Office of the Auditor-General about wasting 3.8-billion-baht from the election budget if the Feb 2 polls go ahead, but are not valid.
it also expressed worries over a recurrence of violence like that seen at the Thai-Japanese stadium, the registration venue for candidates which was blocked by anti-government protesters.
Another concern is a lack of election personnel working at balloting stations.
The letter also pointed to the Supreme Court's Election Division's decision not to rule on cases of unregistered election candidates due to a lack of authority.
Finally, the letter expressed fears that venues for advanced voting, for Thai nationals living overseas, on Jan 26 will be "seized" by anti-government protesters.
The EC's request for the postponement received a cold response from the government.
The Pheu Thai and New Democracy parties yesterday petitioned the EC to go ahead with the Feb 2 election as planned.
Pheu Thai spokesman Prompong Nopparit cited Section 108 of the constitution, which stipulates an election must be held within 60 days of a House dissolution, which was announced on Dec 9.
Mr Prompong has not been convinced by election commissioner Somchai Srisuthiyakorn's argument that the polls should be postponed to May 4 if the number of list-MPs does not meet the legal requirement.
"That's the EC's problem, they must find a way to solve it," Mr Prompong said.
If the EC fails to organise the polls for Feb 2, he will file charges against it for dereliction of duty, he said.