In my senior year of high school, I thought the world was over. After spending years as a cheerleader, I didn't make the squad. But my parents saw my disappointment as an opportunity to convince me that I had a chance to excel on another school team: the debate team. It was an excellent example of how when one door shuts, another opens. My parents did a great job of helping their children shift their perspective. They helped us see politics as more than just talking heads on television. My father, William, served as a Missouri state insurance commissioner in the 1960s and '70s, and my mother, Betty Anne, was the first woman elected to the Columbia City Council. In our family, political service was considered an honorable thing, and politicians were thought of as honorable people who made sacrifices to try to do what was best for our country. It's so important, the things that children see and hear growing up. It's hard for me now, because my kids are so opinionated. Boy, do they argue when they disagree with me, particularly my 18-year-old daughter, Maddie. She argues about some of my positions—for example, the death penalty. She's wildly opposed to it, whereas I support it. But I'm very proud of how she spars with me about it. As a parent, I just beam when she gets on my case. For me, seeing my children develop strong opinions of their own is an important way to see if my parenting has taken hold. Austin, my first child, was born in 1987 while I was serving in the Missouri state legislature. I was the first state lawmaker to give birth while in office. There was actually a bassinet by my desk and a jump-up right in the doorway—a great way to block lobbyists because they had to try to get around Austin in his jumper seat to get in my office. Joking aside, it was eye-opening for the lobbyists and the other legislators. My baby's presence in my office brought the issue of what it means to be a working mother home to them in a way they hadn't really encountered before. I knew that what I was doing would not be practical in most workplaces—and that it could even be thought of as disruptive. But the legislature is kind of unique: You keep your own schedules, and each office has discretion over determining its own work rules.When I declared my candidacy for Jackson County prosecutor in 1991, I was looking after two toddlers and a baby girl, Lily, who's now 15. Nonetheless, I was the first woman to run for and successfully hold that office. It was my dream job. I had developed some really good ideas about adding drug treatment and prevention programs and new child-support collection and domestic violence units, and I worked hard to be tough on violent crime.There were real public policy reasons that drove me to run for that office, but one thing about politics is that timing is everything. You've got to be willing to go for an office when it becomes available. That's a challenge for women who have children: managing the unforgiving clock of opportunity in politics with the responsibilities of motherhood. I spent seven years in office—while I was prose-cutor and state auditor—as a single mom with three small children. I had to make sure my family was available to help with my children. It was probably the most challenging time for me, but it wasn't something I talked about. Frankly, I didn't talk a lot about my kids when I ran for prosecutor because there's this perception that you need to be tough to do that job, which doesn't really jibe with the image of a mother with three little ones. To some degree, my professional credentials have surfaced in the wake of swimming upstream against the stereotypes of women in political office. I've always staked out territory based on my interests, whether they're "traditional" women's areas of interest or committees or not. These days in the Senate, I serve on the Armed Services, the Homeland Security & Governmental Affairs and the Commerce, Science & Transportation committees. We can't ignore that there's still an issue about women in these jobs.At the same time, motherhood has been the most important thing in my life. I now have a blended family of seven children and one darling 2-year-old grandchild. Motherhood permeates my policy views and how I prioritize my time. It grounds me and motivates me. I have a sense of urgency about college tuition and quality, affordable day care because they're real to me. These issues are in my heart. I've found in my career that you can do pretty good work when your head tells you to do it, and you can do good work when your heart tells you to do it. But you do your best work when they're both talking to you—and you're listening.

Guest columnist: Democrat Claire McCaskill, 52, was elected Missouri's 44th senator in 2006. When not in Washington, she spends her time in St. Louis with her husband, Joseph Shepard, and their large blended family.