If you are a project manager dealing with what you perceive to be an unrealistic deadline, the first thing you will want to do is talk to your sponsor to see if there are any business factors that are driving the deadline. For example, there may be some event occurring that this project needs to support. On the other hand, sometimes managers set arbitrary end-dates just to provide what they consider to be stretch objectives. You may find that by better understanding the reason for the deadline, you may have an easier time getting the team motivated to achieve it.
Once you understand the cause for the deadline date, there are project management techniques that can be utilized to increase the chances of success.
Increase resources. If you find that the deadline is not in alignment with your resources, talk to your manager about increasing the resources that are available for the project. Adding resources to the project may increase the cost, but may allow you to hit the deadline. If the deadline is most important this may be a viable option.
Reduce scope. Talk to your sponsor about reducing the project scope. See if there are features and functionality that he can live without for now so that you can deliver the project within the deadline specified.
Identify and manage the deadline as a project risk. Utilizing risk management will help better manage expectations early in the project and also be a way to gather input and ideas for ways that you might be able to hit the deadline.
Manage scope with zero tolerance. On many projects, you start with an aggressive delivery date, and then the situation gets worse because you do not effectively manage scope. It is absolutely critical that you manage scope effectively and do not increase scope without an appropriate increase in budget and timeline.
Manage the schedule aggressively. In many projects, you might get a little behind but have confidence that you can make up the time later. However, when you start a project with the deadline at risk, be sure to manage the schedule diligently. You have no margin for error. As you monitor the schedule, treat missed deadlines as problems and work hard to solve the reasons behind the slippage.
Look for process improvement opportunities. Lastly, take a hard look at your schedule and your approach for executing the project. Talk to your team, clients, and manager about any ideas they may have for making the project go faster. This will get everyone thinking about being part of a solution.
Although it appears that you are being held accountable for events and circumstances that are not within your control, you do have control over the processes you use to manage the project. Use them proactively and wisely.